http://www.appliedgmc.com/prod.itml/icOid/799
(Its a gasket with a built in block off for the heat riser)

 

It'll fit, but those plates tend to burn through.

- Eric

 

So what is a good solution to blocking off the crossover?
All the solutions not involving a new manifold seem to have problems in durability, or rattling.
Can the port be blocked on the head side?
How about machining the intake and welding in a thick plate?

 

My Machinist did just that, on the performer for my 455, he machined a relief in the cross overs and welded in a thick aliminum plate, then the mating surface was machined and it was like the cross over never existed.

while he was doing that I also had him machine off the edelbrock and performer raised lettering he sanded and blasted it and it is like it was never there, I was trying to keep a stock apprearance. and it looks at first glance like a stock factory aluminum manifold.