Rebuild time

Crawl, walk, run, then run real fast....
You can get away with a lot more on an old school N/A car than a turbo Buick.
Get away with, and turbo car= disaster!,
EXPENSIVE disaster.
a street car/rocketship must be purpose built for that task and requires a specific approach of power, where it is applied, and getting the car to put the power down in the areas of the road over a distance chosen to achieve the et.
there are many levels of street fast.
applying power on a racetrack is very different and requires a different ramp of power.
You must choose where you want the car to actually shine.
Then I will be happy to recommend a strategy untill then a parts list for unknown power and et is close to worthless.
That will save you time in the long run and it keeps the downtime to a minimum.

Now decide on a hp goal. If you have never had a 700hp car build the motor and spec a turbo for it and use some self control to run at low boost levels and they you can turn it up to where you want it.

Decide on the fuel you want to use based on availability of it around you. If E85 is easily accessible use it. If not, pump gas and alky will get you there as well. The answer to that question will determine fuel pump or pumps, alky control kit, and injector size.

Here is what you need.

A good 109 block that is not bored .030 over
Forged rotating assembly.
3.59 stroke crank
6.350 forged rods
Forged pistons 9 to 1 CR
Steel center mains
ARP main stud kit
Ported and polished iron heads with new valves, retainers, and seats.
ARP head stud kit
Ported and polished intake manifold
65 or 70mm throttle body ( Machine the stock one or buy a new one)
212/212 hyd roller cam or better 218/212 is my fav
Roller rockers
New pushrods measured to fit.
RJC deep sump oil pan
Reworked front cover with high volume/high pressure pump
Turbo? HPT 64/66, or Comp 64/64 triple ball bearing will get you what you want. There will be many opinions on turbos here, do your research and go from there.
Your transmission will need to be built with all the hard parts to handle the torque.
PTC 9.5 lock up converter so you can have the best of both worlds. Lock up for cruising. 3200 stall speed to get the turbo to spin quicker.

Fuel pump can be a double pump set up or one big single. On E85, I would suggest a -8 feed/-6 return from the tank and back. Hot wire kit is an absolute must.

And then a good aftermarket ECM to make it all work. Look at MS3 or ECUGN they are priced right and do a real nice job. Holley is good too but it aint cheap. Go with what your builder will support and tune. If he does not do that there are other places that will tune it for you.

The ECM is necessary to tune the car and to data log which will be important. And in this scenario, you will start at low boost levels but want to turn it up to achieve rocket ship status. Tuners can remote in to make changes on it and you can send data logs to them so they can make informed decisions on it.

Cost? You will spend $25K to $35K to get it done.
i have bought a new 200R4 from Art Carr with all of the performance upgrades. I also bought new Champion aluminum heads and intake but that’s where I’m at. Thank you.
Bob1987GN , where are you located ? Help might be right around the corner .
Before we go any further with "help", we need a few questions answered honestly.
How fast is a "rocket ship" to you?
Have you ever driven, owned, or ridden in a car that fast? And actually seen time slips from that car? Not "I beat my buddies car and he says it runs------.
What are you willing and able, right now, to spend on the project?
Do you realize that just about any reputable, capable, and honest, machineshop, and not just the Turbo V-6 ones, are typically six months to a year backlogged?
Are you aware that many of the parts you will need will be on back order also, some up to a year?
Are you aware that having H.P. without a well setup suspension is near useless?
Are you aware that you will be spending another $9000.00+ on suspension, tires, exhaust, headers, and other ancillary support items. Like: fuel pump, lines, regulator, upgraded computer, turbo, intercooler, mounts, rear seat brace, 5th position chassis bushings, driveshaft, axles, C clip eliminators, possible rebuilding of the front end steering parts, brakes, roll bar, harnesses, ad nauseum? AND labor to install these parts if you can't!
The long block is only part of the equation!
And lastly, CAN YOU TUNE THIS "ROCKETSHIP?" Or will you have to find someone CAPABLE, and pay for that too?
On this, as any other, board, some may tell you what you want to hear, the rest will tell you what you need to know.
This is not meant to discourage, but to prepare you.
For instance, something like this.

With obviously a lot of cash outlay, why didn't you go with a custom high quench piston?
I was going for a CR of 9 to 1 since this will be a pump gas/alky set up. Using a 218/212 roller cam in this as well.

I am not sure how to answer the question about a high quench piston. I guess I have more to learn now.

Further research is now required.....