No need to use MLS(multi-layer-steel) head gasket on the 3.0l Vulcan, use composite gaskets
When car makers, or racers, started using aluminum heads on cast iron blocks the head gasket would fail after 20k-50k miles, even faster on racing engines with high ratios
Problem was the expansion rate of cast iron vs aluminum
Aluminum expands faster and 5 to 7 times more when heated than cast iron
So each time an engine was warmed up the composite head gasket was RUBBED as the aluminum expanded faster
So after enough drive cycles, warm up/cool down, the head gasket would rub thru and fail
MLS was used so aluminum head could SLIDE on the head gasket as it expanded, instead of RUB
But there was a problem with straight MLS gaskets, cooling system could leak in colder climates as aluminum shrunk down even more, lol, so not uncommon to have a COLD coolant leak between head and block
So MLS now has a bit of composite material
3.0l has cast iron head and block so use composite
MLS is not a "better" gasket, its a specific use gasket
If you have aluminum heads then use MLS regardless if block is cast iron or aluminum, because the head still expands faster and more than the block