Chainsaw Repair

If you recall I had a small engine shop calling about wanting a plastic worm gear for the jonsered 2083. I have them but dont want to sell anymore of mine. Being I use these saws still.  Both are NLA metal and plastic. But the metal ones was used on the early run of the saws. Jonsered 2077 Poulan 415 475.
So I been wondering if we could reverse engineer this.   Metal in place of the plastic worm gears.  The later 2083 2077 poulan 425 445 505 used the plastic gear and updated pto crank bearing and seal combo.   
Here is the early 415 475 updated replacement that was offered, then 415 475 metal and then the latest one.
It does work on the 445 I just tested on. No cutting trials though. Both saws are still projects but the 445 is running.