Motor Mount Help

I'll get right to it. I've been reading alot of conflicting information about motor mounts. I've got a 1964 barracuda that came with the original 273 and a running 318 from a 87' dodge ram. Some have told me that I will have to modify the right(passenger side) mount in order to reuse the mounts that came off of the 273, while others have told me just the opposite. I've also read that there should be no modification at all to use the mounts from the 273 right onto the 318. Can someone clarify what is correct? or should I get the mounts from schumacher? Also, I've read that all 273 were cast with 4 ears for the passenger side mount, mine only has 3, 2 towards the rear of the block and 1 towards the front. Is this just a fluke or just a 64' year cast?

I'm ready to pull the engine from the truck but want to clarify a few things first before I do in case for some reason I can't use it. Especially since the truck has a nice straight body.

Thanks for any help.