Lazer

So I’ve brought this 77 911s back to life after 23yrs. New fuel lines, tank, distributor cap, leads, injectors, electronic points, smoke tested for air leaks, found minor ones around injector casings so applied putty temporarily. It ticked over well, lumpy acceleration until 300rpm which I presume is it’s too lean or has air leak which I can’t find with smoke.. I adjusted CIS plate to factory spec, rebuilt fuel regulator, and vacuum actuated pressure control valve on left of engine with new parts. checked air valve operation. Checked fuel pressures, all good. Now when I went back in to adjust mixture I think I may have gone wrong way, it was initially popping a bit in exhaust, after leaning it out it had massive bang when starting cold next day and blew off the pop off valve flap and broke the hinges. Man that was noisy, scared heck out of me now I’m in shock!

I did check CO reading with gunson and it was good. Timing also checked.

question is, do you think I’m ok to richen it back up and test again when I fit another pop off valve.