[Nima]

Very good information.
Piecesparts, to answer some or your questions, I don't know anything about the engine internal since I bought the truck with it. I have the edlebroke performer intake and eldlebrock 1406 600 cfm carb. I don't know the jet sizes but they are what the carb came with them when I bought it. Downsizing the jets is what I was thinking about as my next step since fuel injection is out of the picture at this point financially. I have the initial timing set at 12-15 and total timing at 35-37 at 2500 RPM. I have HEI ditributor and I changed the spark plugs and gapped them accordingly when I did the upgrade, I don't remember the numbers since it was while ago. I don't know the heat rating or the plugs. Thermostat is 180 degree. I put 87 gas. The air filter and housing is the edlebrock, the one which is open all around.
My exhausts pipes exist behind the rear wheel. It is a very good point to have them exist straight out back. The exhaust pipes and mufflers are JCWhittney (if I remember correctly since it has been few years). Does muffler can make a difference?!