Ditto to Weston's replies. You can lay the engine on either it's left or right sides and split the cases. The trans will stay in either side. Also, use grey RTV. I have found it works best when used as the one and only form of "gasket" on any metal to metal mating surfaces.
Oh yeah, if you intend to lay it on it's left side (so the trans stays in the left side case), you will have to be sure to remove the 12mm hex head "plug bolt" along with it's copper washer, spring, and check ball. That is there for the reverse shift drum, and needs to be removed when taking the right side case off.