Victory Trans let me tell you where my Dad and I are at with his car and you take all of this for what it is worth.
1. You do not have injectors big enough to go 9's with. 72;s will not flow enough fuel to make that amount of power.
2. We just got done playing around with stall speeds on converters and here is what we have found. 4000 stall is way too much slippage. You can use a 3000 to 3200 stall 9 inch and it will pull like you wont believe. Dads car had an Art Carr 9 inch in it with stall speed of 4000 rpms. It was good for about half track and then the converter would flash right to the redline of the motor.
If you think about it a 74 turbo really is not all that big. A 70-1 can run on the street with a 3000 stall and it is very responsive.
3. You will need a Stage block at some point in your journey. The power levels you are looking for cannot be found with stock blocks and the best porting in the world.
4. The aftermarket heads are that much better. The reason being: the ports on the aluminum heads are just much bigger than stock heads ever could be.
5. Reasons I believe what I am telling you. We are running a Stage 2 block, M&A heads car right now. It may not be as light as yours but it is close. We just dynoed the car and at 26 psi it made 564 hp and 604 ft lbs of torque to the wheels. And we were running rich with that fuel map. This is using a 72 turbo.
The cam we are using is a 224 flat tappet cam and it makes max torque at 4700 rpm. Check out the graph at
http//:[url]www.dynomight.net[/URL] . Click on the GN picture and check it out.
Of course this is just my opinion.
Good luck