SB Advice.

Without being able to determine the condition of the 360, you are buying a "pig in a poke."

One problem you'll have with swapping these engines is the converter balance. The 360 requires a weighted converter --or an aftermarket flex plate from someone line B&M which IS weighted for the 360, where the 318 uses a "neutral balance" converter. You CAN just know the weights off the pu converter, and buy a BM plate for your car

The second problem is oil pans. Neither pan will fit the other engine, IE your car is front sump, the pickup is rear sump, but a 360 has a smaller "half moon" at the rear of the pan than a 318. I DID successfully make a jig, years ago, and cut a section out of two pans, swap them, and create two new pans, IE a 340 rear sump pan for my Landcruiser, and a 360 front sump pan which went in my 70 RR If you can weld/ braze sheet metal, and have a bare block to use as a stabilizing jig, have at it.

Other than that, most everything else is a bolt in/ swap.

Ask yourself WHY does this guy want to do this? I see no good reason for downsizing a pu from a 360 to a 318, unless the 360 is ready for an overhaul --- or worse.