New to me engine

[Pvmt-Pndr]

Update and questions.

The truck fires right up whenever I hit the key. It sounds pretty good too. Once in a while I'll get a pop out of the exhaust. I can't really touch the gas pedal until it's been running for a minute otherwise it stumbles, once it's over that it has great response sitting there.

I've only driven it a couple of miles since I had a long list of things to do to it but that list is short now. I don't have a plate on it but plan to do that this coming spring. This truck does not like to rev. Once I hit my higher gears it is very slow to gain speed. I have good fuel pressure, new plugs/wires, headers, full 2-1/2" exhaust all the way back with an H-pipe. It is still timed at 8 degrees and I hooked up the vacuum advance so at idle it's at 12 degrees. Even with the 4 barrel feeding the motor with everything it has it takes a country mile to get to 45 mph.

What I have yet to do is replace the cap/rotor. I'm running the HEI cap that came with the first motor. I think this is a good place to start to find my power loss but any suggestions beyond that?