Ben,
This is the guy I get my 944 donor parts from. MarkSemi local to me, always has a few parts around, he has a small warehouse full of parts. Hard working guy, just trying to scrape by. It is a father and sons operation.
I have gotten things off of him for 914 projects all the time. 924/ 944 manual sunroof parts check $25 bucks, 944 spare check $35 bucks for the steel one. I need a new 17" one. Full roof clip, with a perfect sunroof, check, even got the bag. I think I paid $100 for it, it might have been less than that.

I am sure he has a gas tank or three

As far as fixing it your self. The only way I can think of doing it is building the section with the fitting, and plastic welding it into the existing tank. So build the panel and fitting first, then patch it into the tank or over the tank where the original came out. You could butt joint it, but why

Thanks I will ping him. I am flying to Cleveland on the 11th not sure how far of a drive he is away but I have 6-7 hours to kill the 11th so maybe a drive by him..