The 86-87 Buick V6 as I am sure he wants to install is not a "simple" bolt in. There are many things to be taken into consideration..........most are easily over come with money.
First off, the late model 3800's use a front wheel drive style bell housing and not the B-O-P style the 86-87 RWD V6's used so I trans swap is also in order.
You will have to contend with adapting the factory electronics unless you decide to go the DFI route that Steve Kaminski took with the Firebird the GM High Tech featured.
You will also be into fabricating exhaust, ac lines, power steering lines and probably a lot of other items that are slipping my mind now.
I am almost finished swapping a GN drive train into an 88 Monte SS and this is almost a bolt in deal. The hardest thing was all the little nickle and dime stuff that you dont realize is different.
I have well over $5k into this swap and its still not complete. That is taking into consideration freshening up the engine, since like most people, I started with an engine of unknown origin.
I see a lot of people who want to do such a swap, but dont take into consideration that most of these engines are atleast 15 years old now. Most will have high miles and even though you can buy a complete one for $1500-$2500, you have to keep in mind that you could be spending another $3-$5k to rebuild it properly. Then you have the transmission to contend with. A proper swap would include a TH2004r. Some have used the old TH700r4 utilizing adapter plates, but the TH2004r is really the correct way to go. That would mean getting a BRF or TAF unit and doing a proper over haul on it which is more money. There is still the issue of the weak 7.5 rear that those F bodies have.
Then the last issue is if you plan on doing the swap yourself or paying someone else to perform it.
Its definitely a nice swap, but I would think for the money that you could buy an older 93-97 V6 F body for under $5k and sell off the SS and use the money towards the swap OR add some sort of power adder to your SS. Again, this is all my $.02
Others opinions may vary.