I did a lot of searching for a part# of what would work, and found some bad info along the way, so I'm posting this for future reference:
The goal is to find a flywheel:
157 tooth to match the bellhousing and starter
6 bolts at the crank - sames as 302/351 for mounting (and the 300 six)
Internally or Zero balance
10" clutch is what I have been told I need to fit under the bellhousing (mine is a crossflow Aussie engine, its a small bell!)
There are probably some cheaper flywheel's that will work, but I could not get those sellers to tell me if a 10" clutch will fit, but I found a chart here that makes it look like a 10" will fit the same places as a 10.5", but I didn't want to roll the dice on it without verification.
sbftech.com/index.php?action=dlattach;topic=21755.0;attach=37899
THIS IS A PDF download. It shows a 10" and a 10.5" having the same bolt pattern dimensions, with 3 groups of 2 bolts. It is different than what they call a 10.4" clutch from an 86+ mustang. So when a flywheel says a 10.5" clutch will fit (and I don't know that it will fit in a US250 bellhousing), according to this chart, a 10" will bolt up also.
So I found a PRW 1628982 SFI-Rated 25 lbs. 157 Teeth Billet Steel Flywheel for Ford 302 5.0L 1980-95. PRW has a good name, and this flywheel has the weight that unbolts to make it zero/internal balanced. And PRW publishes that a 10" clutch will fit. It is normally a $221-$260 flywheel, more than I wanted to spend, but I found a "used-new condition" for $135 shipped, that I think was an open box or damaged box, return or something. It is not here yet, but I hope its as advertised. I plan to have the balance checked before installing.
There is also a speedmaster pce229.1009 that looks like it would work with the weight that unbolts, for around $125, but it did not have as good reviews, but is probably fine, and I don't think I confirmed a 10" works. Also a speedway 6051520, again, not 100% sure a 10" clutch fits. You should be able to google those names and part # and fine em. I would have bought the speedmaster probably if I hadn't run across the PRW like I did.
As a note, when I bought my engine I read that a 300 flywheel will work, so I was expecting to find a flywheel for like $100. I could not find a 300 flywheel in 157 tooth, all were from trucks and 164 tooth. So if you are using a truck bellhousing that requires 164tooth, a 300 flywheel should work, but not if you are using a car bellhousing, which I think is what all the 250 bells are.
I will up-date this at some point to confirm the PRW worked out.
Thank you for the input above!