I believe the Hunter 27-2 (1989-1994) and the 26.5 are both essentially the same hull as the 28.5 you are looking at, just 1.75' shorter, Offhand I don't know of any difference in the layout except I believe there is an extra shelf space in the galley, and a little extra space in the lazarette. I doubt you would much notice the difference between them.
Opens you up to a few other variants of what is largely the same hull.
I'm not sure about the other models, but the 27-2 came with the option of an inboard diesel or a fixed mount remote shift / elec start 2 stroke outboard. The outboard actually works quite well with the addition of a 4 blade prop and has almost none of the drawbacks normally associated with an outboard (less charging output, and burns a little more fuel but that's about it), and has much lower maintenance costs than the inboard, as well as some extra space below decks that isn't otherwise taken up by the diesel engine. For an inland lake I cannot think of any reason the outboard wouldn't work quite well for you (it's working quite well for me coastally).
The only downside is that the outboard models were stripped of some features from the factory, where the diesel came stock with them (flushing head, pressurized water, shore power, etc), but it's nothing you or a previous owner couldn't add if you wanted.