I believe the hull your looking at is a Eliminator Sport Cruiser 20.6 splash. If it is, its a great hull. 18 degree bottom with rounded keel, 4 full length lifting strakes, and reverse chine.
Its a good all around hull that is relatively low profile but still passes on a good ride in modestly rough water.
With a stock 330hp motor and a tight pump you might see 55mph. With a 390hp magnum 56-58mph.
They are great for skiing, tubing, and all around use.
Not that sure of Bahner's quality. But things to check for are hook in the bottom, take a close look at the pump (impeller, etc), obvious hull repairs, stiff steering/forward reverse shifter operation, quality of interior install (make sure the wood is resined and check for wood rot), etc...