Sounds like you just need to dial in the timing a bit. I would get a spring kit and do some test and tune. disconnect the vacuum adv. and set the timing so you get about 36 degrees total advance in between about 2,500 to 3,000 rpm's. probably going to be about 14 BTDC or so at idle depending on how much mechanical advance the dist. has. if the timing comes all in too late put on a weaker spring, too soon a stiffer spring. if you want to run a vacuum adv. hook it back up and test drive it, if its adjustable you can back the amount of advance off and try it then. if your not worried about every mpg I would disconnect the vacuum and run it to the specs above. in that range is what most mild built small blocks seem to like.
