I'm just hatin to see you spend what......300 plus clams and still not solve your issue. Did you block the exhaust cross over in the intake you have now? That could actually make a difference.
Yes, spending coin on the unnecessary is useless. A 'plain' perf/rpm/air-gap is $450. Long ago I had a 'plain' manifold...and the resulting stains and ugliness was not something I will repeat. I'm not much interested in a show-n-shine engine, but much less interested in yucky ugly. So...throw in a polish and a clear powder coat and it's a lot closer to a $grand.
Yes. I am 'moving forward' with the basic common sense stuff...things that should have been done already: Phenolic spacer and a regulator/gauge. The bypass part will be a bit down the line. First I want to ensure the carb is reasonably isolated AND that I have <5psi at the carb.
The thermo pen idea is spot on. IR units do way too much bouncing around when shiny things are involved.
IF responses to my original question abounded with 'air-gaps are the only way to go' and anecdotal input as to a plethora of problems solved, I would be tending toward getting one.