I wish you were closer. I'd love to go up there and play with it. I am very well versed in early 80's GM engines. I've owned my 81 Regal for almost 19 years, I grew up helping dad work on our 1980 Pontiac wagon, my 81 AMC Spirit had a Pontiac Iron Duke (151) in it, plus the experience I picked up working on my 74 and 86 Chevy trucks... I know a lot about early 80's GM.
If the engine is running reasonably smoothly, I wouldn't think there'd be a problem with the plug wires being crossed up. The lack of power above 45 mph sounds a lot like clogged fuel filter, which in my limited experience causes a car to run fine at idle, or slow speeds, and like a dead dog climbing hills or on the freeway.
__________________ "We are forces of chaos and anarchy. Everything they say we are we are, and we are very proud of ourselves!" -- Jefferson Airplane
Dick Naugle says: 1. Prepare food fresh. 2. Serve customers fast. 3. Keep place clean.
HC's car has a mechanical fuel pump mounted on the side of the engine block. The fuel filter is located in the carb. Look at where the fuel line goes into the carb. Disconnect the aluminum fuel supply line from the carb. You will notice that the fuel line is screwed into a large brass bushing on the carb. Remove this bushing. The fuel filter is behind it. Make sure the new filter is put in facing the proper direction. The check valve will be facing out, and the brass endcap on the filter will be towards the back. If put in backwards the engine probably would not run at all.