The answer is a little complicated. You can, but you won't be able to use your mid section. The 225 uses a 5" spacer already on 20" midsection. Maybe you can find 10" studs and a 5" second spacer, but those studs will have to be custom made.
The way I would do this . . . is by using a newer 25" midsection (I have a bunch of these) and using the a 5" spacer and studs on the existing 25" V225, a
a 28 5/8" copper tube (water tube), and a 5" Drive and 5" shift shaft extension from Bay Engineering.
http://www.baymfg.com/mercury.asp
One thing I am not sure of is how well these extension shafts work with your older preload Pin style lower units (1983 and earlier) . . . good question to ask BayMFG
If you want I'll be doing this conversion for mid 80's 200hp in the two weeks (from 25" to 30"). I can post a how too tutorial.
The hardest part is going to be removing the powerhead from the mid section on your motor. 28 years of salt and dissimilar metals will have made enough aluminum oxide powder to put a permanent choke hold on those powerhead bolts. PM me . . . I know a few tricks if you decide to do this.