I have several rebuildable 196s sitting around, but I understand that there is something unique about the '62 version of that engine - perhaps how the crossmember fits under the oil pan or the locations of the engine mounts - that prohibits easily dropping in a 196 from an earlier year.
I don't know 1962/earlier, but I do know that what you CANT bolt-in are 1963-up, when they went to "tri-poise power" aka modern three-point mount (two in front, one on the trans). Before 1963, Rambelr used the old system, where the engine sits on pads, and the trans more or less hangs off the back.
The short of it is, 1962-earlier engines should fit. The old mounts are towards the front of the engine (or on the very front) and the modern, 1963-up, are in the middle of the blocks, on the sides.
I'd wait to hear from an expert, and I wouldn't go ahead on just my own advice (!), but you can probably eye-ball the mount situation with the motors you have and tell.