[hatzie]

Your bellhousing is not likely the source of your problem.
There are two different Chebby flywheel sizes. 12-3/4" 153 tooth and 14" 168 tooth. Are the original starter bolts diagonal to the crank or Perpendicular?
Diagonal or staggered bolts, depending on how you want to look at it, are used on starters for the 168 tooth flywheel.
Perpendicular to the centreline of the crank is the starter for the 153 tooth flywheel.

The stock GM gear reduction starter on the 1990 Corvette is less than a stellar performer when it gets hot. Much worse than the big heavy old Delco that came with your truck.
If you want a lightweight fast cranking starter, that doesn't get angry when you get it hot, get a gear reduction unit from an outfit with a good reputation or get your original unit rebuilt locally.
Whatever you do don't let the original unit go as a core. You'll end up with a cheap Chinese piece of garbage without the means to go back to the big heavy parts in the 1982 Delco.