Since the motor has been out before, rebuild it and drop her back in. You likely won't hurt it with what you are planning to do with the car and lets face it, with the sophistication of restamps now, many don't believe that any motor that has been touched is the guaranteed original. I've looked at tons of original stampings and have always valued original motor cars significantly more than non-OM cars...until this past weekend when a guy I know showed me his newly restamped/broached motor

It was darn good and I bet many experienced gearheads would think that it was the original stamping! I'm starting to value paperwork more than motors now on restored cars