Buy a 1978 Ford Shop Manual-the schematic might be in there. If not, look for a 1978 Ford Vacuum Schematic. A V-8 swap would be easiest if you had a v8 mustang ii parts car as there is A LOT of parts you'll need to switch over-the special 302 engine mounts, special double hump
trans mount, correct radiator, special exhaust manifolds, mustang ii specific v8 bellhousing and v8-4 speed
trans, mustang ii specific 302 oil pan, complete suspension, and more. Most of these major parts are specific to the mustang ii because of the very cramped space and if you buy everything off Ebay you'll spend a small fortune gathering all that you'll need. Ebay is a great place to get any parts but find a mustang ii v8 parts car-the well optioned Ghia usually would have a v8 in it.