If you were swapping engines in a '54, '55 or '56 car frame, the motor mounts are the same regardless of which engine you are swapping to. But the '53 had the older style frame they started using in '49 and I am not all that familiar with that frame.
It seems to me that the early overhead six was a 215 CID (offered in the '53 and '54 Fords). If I remember right, the 215 and 223 engines were nearly identical, except that the locations of the fuel pump and distributor were swapped and that the motor mount location was a little different. Somethin you might want to look at.