Engine swap

i think he meens a 318 with out mods,,as in a stock 318 engine,, if thats the case,,do what ever you need to the fire wall,,im not experienced in tthe 63 fire wall,,but not strange that its different form 64 and newer,,,

the 7 1/4 rear will be fine with a stock 318 if you drive it normal,,, i had a 340 with a 7 1/4 that was fine,,,as long as your not putting any big sticky tires that stock rear will be fine,,,you will need a trans for a v8 and a drive shaft,, motor mounts,, and the stock torsion bars will be fine for a street driver,,,drag racers have been using the 6 cylinder torsion bars for years with a v 8 they make a v 8 car lift nicely in the front making better weight transfer,,