I have an older Honda 100 (Ser.# B100S-16027xx) 4-stroke which runs well but I need to convert it to a long shaft. I believe the year of manufacture is 1984.
I have a similar motor in a long shaft (Ser.#B100L-13005xx) with a seized engine that I can use for parts. I believe the year of manufacture is 1981.
My questions are:
1. Are the shafts on these two motors interchangeable?
2. What parts (gaskets etc) would I need to complete the conversion?

BTW, I also have access to another short shaft motor (Ser.#B100-10092xx) that I could convert if the other one is not compatible. I believe the year of manufacture is 1978. Would this one be compatible?

Thanks.