Convert merc 37L to 120140 configuration

"Found a 1986 Wellcraft 19&#39

"Found a 1986 Wellcraft 19' bowrider, in absolute pristene condition, from the bow right to the propeller tip!!!!! (quite cheap) That's the only reason for this post. It's power is a (tag missing) 470-485 etc., one of the 3.7L, 4cly alum block, heat exchanged motors, and it's SEAZED.
So the question is: Knowing that the parts for the 3.7L are scarce and EXPENSIVE, is it feasable to convert this boat to the GM 120-140 motor? (multiple used units in my area for short money, I have the capablities to rebuild anyway). Do I start, and where do I start? thoughts and comments and help would be most appreciated. Stu"

"To swap to a 140 you will nee

"To swap to a 140 you will need to change the exhaust pipe on the transom, glass in a new front mount pad (the 140 is shorter) and regear the drive from 184: to 198:. That said, you will probably lose some mph but, reliability and cost per repair will be much better with a 140. I have found that with the least amount of care these (140) motors are great. With proper care and feeding it will last forever."

"Where do I start? do i have t

"Where do I start? do i have to change the transom mount plate (bellhousing)?
For the lack of a better term, the drive shaft from motor to drive? is there any literature that i can get to help?"