318 to 360 swap

318 motor mounts will work, just need a spacer on the driver's side (a nut will work). Other stuff you may already know, you'll need a balanced flexplate or balanced converter as the 360 is externally balanced (unless somebody internally balanced yours). You'll need the 360's harmonic balancer. You cannot use the LA 318 pan on a 360.
Why not just get the correct motor mount? Seems odd to me that people will spend thousands on their engines and then try to cut corners on the smaller parts. The driver's side is the torque side and you surely don't want it failing under acceleration, in order to save a couple of bucks.