Most all the heads swap among the 4g63 and 4g64, so making one a dohc 16v is no trouble. The trouble arises with the water outlet, which is on the rear of the head, and you have to get creative.

I repeat, all this is covered in projectzerog.com, mostly pioneered by the starquest crowd. There are low profile outlets with remote tstats and a way to remove a freeze plug in the front of the head and install a tube there.

I thought the 2.4 wide block fit the 2.6 bellhousing pattern - pretty sure as a matter of fact. You can still use the km148 from a v6 with the I4 bellhousing, but you are still stuck with the km145 m/t, unless somebody has come up with a 2.6 bellhousing that will fit on the v6 heftier 5spd. I think the tranny came behind one of the diesels, so that's a possibility.