Changed intake gasket, now it won't start

Been way working for some days. OP, your cylinder compressions numbers are good. Contemplating pulling the motor based on what you show as compression numbers and the plug colors and symptoms makes NO sense.

The symptoms of running rough after replacing the intake gaskets twice still points to intake manifold leaks as one probable cause. The plug coloration likely indicates a mix of normal cylinder-to-cylinder variations and some degree of ignition and carb mistuning, in addition to intake leaks.

At this point, I would advise enlisting some local KNOWLEDGEABLE help or taking it to a local shop that knows these vintage of engines. Your have done a lot of work I know, but the level of good ideas seems to be dropping off; it needs a detailed and methodical process of troubleshooting. It has taken well over 100 posts to get to the point of a comprehensive set of compression numbers, and explaining how to go through a tuning process, figure out if there are still vacuum leaks, see if the 'blap, blap' sound is just exhaust leak, etc., is going to take several hundred more posts at the current rate. If your father-in-law builds engines, is he near enough to help?