Most of the \6 guys don't know what they are talking about.
I think you should use a Holley double pumper, about 600cfm. Use the Offy manifold. Modify a big block mechanical high flow fuel pump to accept boost referencing and use the MSD 6btm with the electronic ignition distributor. The TO4b that does10 recomends is just about right, a second option is the '83-'84 Buick 3.8 turbo. A "J" pipe from the stock exhaust manifold will work great. But you need to remember that the stock manifold will start to sag and eventually fail. If this happens you will need to build a manifold out of 14g mild steel round tube or schedule 40 pipe. Both of these will last a long time.
This should get you to 10lbs of boost and about 250hp. At 10lbs of boost an intercooler is optional, you really don't need one until you start to hit 15lbs or more, especially on a carburated setup. The very nature of fuel atomization lowers the inlet charge about 30*.
If you want to make more power you will need to start modifing the head. This can be done with basic port and polish and adding the 1.7/1.44 valves from SI. You may want to contact CompCams about a custom grind for any camshaft changes.
Remeber Tom Drake has run low 11s, high 10s with a basically stock 225 \6 with EFI and menthanol at 13lbs of boost.