76 292 intake/exhaust recommendations

[cerial]

I picked up a 76 c30 last night with a 292. The thing has what sounds like a exhaust leak and it seems like the linkage or something on the carb is off.

It runs great does not bog down, surge, or anything. It idles great right after you start it. But after I get up to 2k or so then drop the rpm down to where idle should be the thing keeps dropping and the truck dies. Turn the key and it fires right up. Get it back up and drive to the next light or just put it in neutral, it drops down and dies.
I will play with it this weekend. It had me avoiding stopping as much as possible during the 45 mile trip to the folks place.

The thing has all stock parts on it and I would like to add a little bit of performance in the way of a intake/headers. It has been a while since I have had a engine without secondaries and would not mind a 4 barrel 300-500 carb.

The good thing about the 76 is that the valves are good for today's junk fuel. But, it seems something changed in the intake as most sites go etc-1975. I need to retain the ablity to start this thing in temps from -20 to 90F without babysitting it and the intake/heat riser/exhaust all come into play in that.

Any recommendations on intake/carb/exhaust?

What is the reason I can't run the "earlier"(before 76) aftermarket intakes?