sb tuning problems

Jet it down, adjust idle mixture for highest vacuum reading or highest smooth engine rpm. Timing should be no more than 36 degrees at 3000 rpm. Don't use any sort of heavy springs in the distributor, medium to lightweight. You should be able to run at 14-16 initial without any problem. Betting a majority of your issues are carb related, possibly a vacuum leak showing up when the engine warms up... What's your fuel delivery system, line size, pump, regulator, return line?

If you are still running the 1050 you have way more carb than you need. Put that 850 back on / stock jetting / 4.5 pv or block the power valve and put the same size jets in the primaries and secondaries. If any of your carbs are edelbrocks throw them up in the classifieds and let them become someone elses nightmare