Would appreciate intelligent input regarding ongoing problems after allowing 2, yes 2 engine shops to rebuild engine in the last 6 years.
Ongoing problems have included mismatched timing and carb setup with tuning an everyday task with no end to driveability issues. Have had so many "experts" advise me what to do that I am ready for a create engine replacement to end this saga. Am told that with the cam I have the ign. timing should be between 12-14 deg and an idle of 1000-1100 rpm. Using 91 grade fuel. If I retard timing to 10-12 deg idle speed is so low around 450-500 rpm the negine stumbles all over the place. If I advance idle speed I get preignition and run on after engine shutdown. I still have light pinging at moderate acceleration. Vacuum is direct to manifold. If I connect to timed carb port forget it the whole car is all over the place at idle. Main complaint is the lack of overall performance. After last engine rebuild was told the transmission should be changed to 700R4 which I did at trans performance shop. No problem with the trans but no improvement in performance. Next I was told to change out the cruiser rear end from the 2.29 to a 3.42 which I did. Still no improvement in performance. DO I just have a dog or what. Hate to have to spend out on engine again.
Wonder if the cam is the wrong type for a street car it's calssed as a bracket racer cam. Most driving rpm range is from idle to around 2500 rpm unless you floor it for get up and go. Am looking for a strictly street car, NO RACING, but one which goes when it should, especially from a standing start. Currently I can run faster myself. I also notice there seems to be unburnt fuel coming out of the exhaust with the smell. No idea what's causing that. I NEED INFORMATION, CREDIBLE ADVICE and HELP, or a NEW CRATE ENGINE.

chev 350 block
OE iron chevy heads
J&E forged pistons
Lunati cam 2000-5500 rpm
Edelbrock intake
Edelbrock carb
dual exhaust with cats