I have already gone down this path.
It’s suggested to use sealant. I messaged MACE about it years ago.
However experience says use double metal gaskets. I had to cut the cantering nib off one gasket.
Nothing worse that struggling to separate the manifold for servicing. Then scraping the sealant off without getting bits down the intakes (even if they are plugged up with paper towel or cotton cloth) is a pain in the butt.
Two gaskets make things way easier and for that reason alone. Have been glad I’ve done it on two of my Commodores.
I only run spacers but it’s the same issue.