We only have a 40 grit aluminum carbide surfacer and we do a **** load of heads with it aluminum and cast iron, funny thing is we have never had a comeback with any head gasket and yes we've built engines with MLS and specifically cometic.
The only comeback was from a new mechanic who just graduated tech school and he didn't even install them he just said " it won't work" but it has on every other LS, hemi, Honda, Subaru, Toyota, jaguar, fomoco, even nicosel aluminum.
