lower unit gear case

[Dobi]

in my Intro to the forum I mentioned this, but figured I would bring it down to here where it belongs.

I have a '90 stratos 201 water tank w/1990 Evinrude 200hp

I have a crack in the lower unit, drivers side, right on the "clutch dogs" I am told.
It was due to the lower unit freezing. I'm a heckuva automobile mechanic but don't know much about marine engines or lower units. Guess I may be getting a crash course in it though. lol

I found someone with a '92 johnson fast strike 150hp that said he would sell me the lower unit for a couple hundred dollars. I know johnson / evinrude were/are the same at some point so....

1) would the lower unit bolt onto mine and fix the problem

if not

2) would the casing work and I just have the guts swapped out

if yes to either 1 and/or 2

3) is the $200 range a good price.

Thanks in advance.!