I think that may work, but the ring (regardless of which shape) "snaps" into the molded rolled outer edge. You would be lacking that "snap" feature. Maybe adding additional screws would be a good idea in that case?
When I did my Sportsman, I did a trial fit of a 16 hole simply to see if it would clear the upper transom strip & it did. My round seal is good, so for now that is what I used. I also have 3 more good used ones.
If you have the nearly square transom seal (not used on OMC built boats), the 16 hole won't cover the cutout. I don't know about the 22 hole seals, maybe they would cover the cutout.
Why so many different seals anyway? I get the need for the round style for small or irregular shaped (not flat) transoms. It's a bitch to remove or install the engine because of the tilt clutch. Of course, OMC was only installing the engine.
On this note, after removing the engine/intermediate as an assembly, I separated the 2 (another bitch after 53 years of dried grease on the splines). It required removing the lower cross mount & working the flywheel bolts out with a deep offset 5/8 wrench 1/6th turn at a time. The intermediate went back in 1st then the engine was installed. Much easier & the splices have new Molylube, good for another 53 years.
The 16 hole makes removal & installation easier as well as replacing the tilt motor on a boat with poor interior access.
Why the bigger nearly square style? Didn't anyone ever explain to the engineers & designers that cutouts should have round corners to reduce stress/cracks?
The larger 22 hole came last, it allowed more clearance to avoid pinching when using power trim.
Having a little time right now I had fun with scrap metal to reproduce the back part of my deluxe. A friend who picked up an old deluxe gave me his that is very damaged so I can have a model. Now i have to see if it fits well on the hull. Not having it at home I will see this weekend. There are still some finishes to be done but it looks pretty good !