The typical changeover parts are needed.....complete engine and transmssion with all their accessories. You can use a car engine if you get all the '61-71 truck-only items...mounts, oil pan, pickup/strainer, etc. Get a truck 6cyl. radiator or modify yours. Same with wiring and exhaust system. If you're replacing one 727 with another, the driveshaft will be the same. If it's a manual trans, you'll need the appropriate bell housing/flywheel/clutch.
If it were me, I'd keep the 318. Mileage is not much different and the extra power is great when you need it.
