400 stroker

not sure if it's available stateside bit i've used wellseal on 4 stroke bike motors with no head gasket at all and they seal fine so ought to work well with the steel shim gaskets. it stinks but seals well so gets my vote.
neil.
wellseal | eBay
Looks like it stays flexible, like Hylomar. That's good. The problem with the steel gasket between cast iron and aluminum, is the different expansion rates between the 2 metals. This stresses the gasket, and eventually leads to a coolant leak, or worse. The MLS gasket has several layers, and allows the 2 metals to slide past each other smoothly, with the expansion/contraction from temperature changes.