I use Cometic and Felpro MLS gaskets on a regular basis for street engines. I've never had one leak.
On big bore aftermarket Windsors, an MLS gasket is about all you can find.
I use a little bit of silicone around the coolant holes and it's very important to watch where the rivets are as they can get in the way of mating surfaces. It's not a problem on FE's, but on Windsors/Clevelands, the rivets can sometimes be located in between two surfaces and they have to be removed before installation.