I had a 1982 Baja BR186 (which became the SunSport a few year later, same hull design, less a few new pieces). Back in 1980's they were still hand laid hulls and were built fairly stout. I could run her at 65mph with a 200HP Mercury and a 21P prop spinning ~6,800rpms... very, very stable...only got chine walk in 1'-1 1/2' chop, easily controllable with trim. An outboard and an inboard have considerably different handling characteristics and I have yet to see chine walk happen as easily and/or as pronounced as I have with an out board.
I think with motor that could run in 70-80mph range you'll find that boat would tolerate it from a strength and durability standpoint...assuming the hull and substructure are sound? Over on the checkmate-********** forum, they call the early Baja's "clones" as their early hull design were 'borrowed' from checkmate...which can be very, very fast boats
Is this roughly the boat?
Have her checked out (mostly for rot) if you like the results, make an offer and see what she'll run...my guess in basic trim 55-58mph???