Help identify Engine

You'll need a ton of parts to get that to fit in a '64-6 A-body. Start with all the brackets, exhaust manifolds, linkages, pulleys, etc off an early 273. Then you get to try and find an oil pan that won't hit the k-member, and get the proper pickup for that pan. You'll need to modify some 273 engine brackets to fit the 360 block, or find some aftermarket mounts. Cooling system, wiring, rear axle, brakes all need to changed or modified to make that 360 happy.