ok it runs but poorly??

FINALLY!!!!! We got it figured out. first of all the pickup coil in the elec dist was shot causing the welding problem. Second the poor running was caused from the following. 1) the flapper on the passenger side of the engine would flap shut when the engine was reved. 2) single small pipe....way to small and restrictive. but the funniest 3)we finally had checked everything else, so we pulled the timing cover today...guess what...the cam was 25-29 degrees advanced......how the hell did it even run to start with. could explain the hard to start thing and the lack of power, and the popping. reset to 2 degrees and put it mostly back together and fired her up....ran like a champ. the guy is not letting me pay him for the work, he decided to take it up with the builder himself. we cut the pipes off 6" below the manifolds to check it, so tommorrow it is off to install the headers, and new exhaust. a few new questions. will the rear end of an E body same year fit an A body? what about exhaust pipes? my new "best friend" has a 1970 Cuda, and a shop full of Moparts. has a pro built 8 3/4 rear end. 11.5:1 500hp 383 with 727 (manual valve body) he has it all. want to install all into the dart next year. I know engine, trans will fit, but want the rear if it will fit as well. it has the pro stock new leaf springs, and racing adj shocks on it. I can buy it all with a guarentee for $1500.00 the engine has 3 runs down the track, trany has none. rear has none. is this a good deal? thanks all for the help. finally it has started to go forward. during this all we came up with a name for the car. From here on out she shall be forever remembered and named......BadMojo!!!