Re: Want to build a Frankenoutboard
Pros and cons: Your 78 is probably a distributor ignition engine--I don't think they changed to Prestolite distributorless untill 79 or 80. Distributor is a little less precise than Prestolite and Prestolite will produce slightly more power, but not enough that you can tell when running the boat
The distributor ignition will not fit on the later block unless you modify the alternator stator mount (top seal).
Other than that, the blocks are exactly the same with only minor carb changes.
However: every block I have ever seen was in excellent condition or ran when it was last stored--I'll respect you in the morning, the check is in the mail, I got an inside tip from a trainer; this horse is a shoe-in, Etc.
IF the cylinder on your engine is not scored or excessively worn, the piston can be replaced through the reed opening without disassembling the engine. If it needs boring, then the engine MUST be disassembled.
If you do need to take the engine apart, then you might as well port it--It will significantly improve power and will not affect service life.
As far as broken and stripped bolts you need to man-up. Drill out broken ones, retap, if possible, or Heli-coil, if possible, stripped bolt holes.
