If the engine and trans were originally installed as a unit, there should be a tag on the bellhousing adapter with the engine serial number stamped on it. That number will match the one stamped on the pad behind the distributor. If those numbers match, it's worth the cost of an engine rebuild just in collector's value to keep them together. Yes, the later engine and trans will probably mate up and run, but you'll probably end up with vibration, and possibly fluid leak problems.
Jerry
