Heat crossover ????

Sunday I need to block the heat crossover in an intake manifold. I can’t do it with a gasket (I could do it with a gasket, but I’d have to machine the intake to fit with thicker gaskets and I don’t want to do that) so I’ve read (IIRC) that some have stuffed the crossover with aluminum foil as tight as you can and it worked.

Any one done it and had it work? I’m also going to test a CoolCarb spacer and that’s why I need to block it off.

TIA
YR