Did Wellcraft glass in their stringers?

[RidgeRunner]

Yes they did, hand layed hulls too, they used some heavy glass (woven roving like 28 oz. layed into mat for complete wet out). They got a little sloppy here and there where the sisters meet the main stringers. But they are built pretty tough. Congrats. on the new project.
BTW- Transoms aren't near as critical on a I/O as they are with the outboard counterparts. In your case, the transom has to be able to hold the gimbal mount and outdrive up. The engine rests on the stringers inside the boat. The main reason so many transoms fail is due to all the holes the owners poke in them and fail to seal the holes properly and the way Wellcraft sealed the top of the transoms on nearly all of the outboard models leaves much to be desired. Yours has a full transom where the cap shields the top of the transom from the elements. That is a good thing.