I'm confused. I see alot of people griping about the transmission. What is the problem with the stock trans in your cars? I have run 2 of them in the rally car and every time we rebuild it, we are amazed that there is no synchro wear and the gears look good. After 2.5 years of rallying, I have a bit of pitting on the ring and pinion, but I am using the Emco r&p anyway. All this on boxes that get 200+ hp put through them, get downshifted often with no clutch, and get shock loads up the yingyang when landing from jumps, etc.
Also, somebody wanted racing axles. The stock axles are extremely strong. I haven't broken one except when I exploded a wheel on stage. The hard outer boots kinda suck, but not worth getting my undies in a twist. Again, if they take the shock loads of full power at full lock and full power on pavement landings on jumps at full droop, they should be more than adequate for your car until you are seeing 220+...and even then I think they will hang in there.
Intake manifolds and T-bodys can be flowed, bored, and reworked/new plate by a reputable cylinder head shop...open the yellow pages. My rally motors all use stock based parts.
The things you N/A guys need to make power are CAMS, COMPRESSION, and ENGINE MAPS (ECU). That will get you a big jump. Beyond that it is real work with changing valve sizes, etc. Again, a reputable cyl. head shop should be able to help you with it, but if the ECU wont give you the fuel or particularly, the timing, you will not get real far...about 170-180 with stock ECU on an N/A engine needing 100 oct. (in my opinion, of course).
Going up from there things get exponentially more expensive.
Turbo cars I would think are limited by the intercooler, the ecu, and then just controlling boost and seeing how hard you wanna push your stock rods and bearings. Again, the ECU would make things better.
Get a Walbro 255 in tank pump and it will drop right into the tank with an extra gasket and a spacer ring...should be good for 300hp.
Less bling, more zing.