318... to stroke or not to stroke???

OK so if I decide to go to the 360, will it matter if it's magen or la? The cam I have is for a la and has hydraulic flat tappet lifters, and before someone pips off with "send it back and get a different kind" I have bought heads that were custom set up for that cam/lifter combo

Since you have EQ heads (magnum style that oil the rockers through the pushrods) it doesn't matter. If you had LA style heads you'd have to use a LA block