just rebuilt runs bad

your alittle to far or I would come diagnos it for you. I live in northeast pa. After reading all of this. It seems to me your machine guys don't want to help you or they would have offered. Something sounds amiss with your chain not working. There could only be one reason. They line bored the block wrong and the cam ended up to close to the crank. Alot of these shops put all 4 bolts in the cam retainer and starve the chain for oil. Sound to me like your cam timing is off. Or your lifter preload is tight.

Also msd box has a cylinder select. This is under the plastic cap Phillips screw. If it was bought and returned or bought used there i a possibility that one of the loops are cut. Your ignition will do what you are dicribing also. 8 no loops should be cut. 6 cut red. 4 cut red and blue. Make sure your wires from your distributor to the ignition box do not cross paths with the coil wire or any other high voltage leads. This will make the timing move around and cause a miss and sometimes bacfires from the plugs being fired twice.