Yeah, I don't think you want to use those intake gaskets unless you are Canadian and not using antifreeze.
I've seen them deteriorate and "squirm" around on my own 428. I'm using Mr. Gasket 202A's now. Much better.
The Mr.Gasket 202A's are easy to trim to the port size, too. Though they are limited in how far you can trim them, if your ports are very big.
JMO,
paulie