Congratulations, CPK!

Since you seem to genuinely appreciate alternate viewpoints, here is mine:

1) Keep your eye on the prize - the v20.
That is what the deal was about for you - right.
Hopefully, the HULL is in as good shape as you perceiv eit to be. You need to focus very carefully on the transom and the stringers - especially where they meet the transom. Now that this is your boat, don't be afraid to poke around. Drilling a small test hole into the transom and stringers from inside the hull is no big deal. Get a real good idea of what you have - before you start investing your resources in repairs and upgrades of lower priority. At the risk of sounding negative, the more you look - the more problems you will find. But don't despair, because a 1987 hull is likely to just be beginning to show problems. If you want this boat for yourself and for the long haul - then you want to find problems NOW so that you can nip them in the bud and prevent them from becoming bigger problems.

2) The motor.

It is too big for your v20. It will cause and accelerate any hull problems. It will burn way more gas and oil then you want to buy. Fix the flywheel and get it running as cheaply as you can. But do it right. You have all winter to do this. You can probably pick up a used flywheel cheap if you take your time and look around. Winter is the best time in the northeast to find a mechanic to do the work if you are not doing it yourself. Hopefully, you have or can get documentation on the rebuild. That will help you on your resale price. With luck, you will get the lions' share of your initial outlay back. Repower with the best carbed 150 2 stroke your budget will allow, AFTER your are satisfied with your hull.

3) THE TRAILER

Looks too small. If you are gonna be any kind of a trailer boater - sell it and buy one of sufficient GVWR for a fully loaded v20.

4) Electronics
Upgrade as you see fit when 1,2,3 are done.

5) kEEP POSTING :)