I know carb boil over is an issue with the nailheads, can you plug the exhaust crossover passages in the manifold to help with this if it's a summer driver? I know about the heat spacers and stuff, but am thinking the cooler I keep the gas the better.
Poston sells an intake manifold gasket set that includes stainless steel plates that block off the heat riser passageways.
Saw some more discussion of this over on the ROA list. Since you heat with a torch to 'undo' JB Weld, I would think that it is risky to use where it is exposed to hot exhaust gas. Might want to use epoxy putty instead, and look for something that specifical states its for use in fixing exhaust manifold. I know so-called hi-temp 500 degree paint burns off with no problem, so I'd look for something that withstands heat close to the 1000 degree ball-park. Or call Poston at 800-635-9781 and ask for part number PE947320.
