Bit of a long leap…why not diagnose the problem first? Overheating is usually not due to something that would warrant replacing the engine. If the engine is worn out or otherwise faulty
and overheating, that's another matter. But what if the overheating's due to, say, a bum radiator? Then all the hassle and sweat of an engine swap will be for nothing; the new engine will overheat, too.
Yes.
Yes, and you will need to make that swap. Take the opportunity to service the oil pressure relief valve to make sure it's doing its job, as described in these two threads:
thread 1,
thread 2.
Yes, though you may need to shorten and rethread the rod that runs down from the throttle bellcrank in front of the firewall to the kickdown pivot at the front of the floorpan. Even if not, that rod will need adjusting to achieve correct shift points.
Not many, really. Exhaust headpipe will be lowered by about an inch when going from a 225 to a 170, which may or may not make any practical issue. Engine mounts are the same.
