Book says to use Wellseal "or equivalent".
My experience has been that if everything else is right, it will seal just fine with or without your choice of sealant. But if something else is wrong, like distorted studs or (as in my case), not enough liner protrusion, then NOTHING is going to make it seal. Copper stuff, silver stuff, genuine Wellseal (brought in from the UK at great expense), Permatex #3, none of them made any difference whatsoever. Best I can tell, the block was improperly machined at the factory, because the liner protrusion is within spec on one side (the side I checked over and over again, naturally) but they are low on the other side.
Head gasket will fit & work either way (some very early gaskets didn't have the redundant oil hole but I think everything since about 1960 has had it). However I've read a line somewhere to put the smooth side down, which makes sense to me. Otherwise, one of the crimped seams hangs out into the water jacket and seems to open up slightly when the head is torqued down.