Well pictures would certainly help all of us, and you. Plus measure the beam at the stern and in the middle to see how wide she is, then measure the gunnel and transom heights. Also look at the 'shape' of the transition as the running bottom turns up to become the sides, is there a square/angled feature there at the garboard or it is rounded? Are the sides ribbed? Are there extensive chines down the hull outside of the keel? Is there any deadrise to the stern ("V" shape) or is the running surface flat at the rearmost part of the hull?
Even if you could weigh the hull that would tell you something. Then if needed, look up equivalent sized/shaped hulls on the brochures here: http://www.fiberglassics.com/library/index.php?title=Main_Page . Look up your Starcraft over on their current Starcraft website, where they list older brochures.
FWIW the non-rounded chine hulls (round chine hulls can be TIPPY! :shock: !), deeper V-deadrise, and taller/wider hulls generally allow for more horsepower, so typically the 'bigger '14' hulls could hold up to a 25hp (Lund SV14 or equivalent Smoker Craft WWR-14 models), even up to the 30hp if run by a side console steering. Boat like this, of typical 3-seat configuration or such have a mid-beam width of 72" (6').
If it appears to be a bigger/heavier/beamier/beefier constructed 14-footer, a 25hp OB should be fine, but if a smaller tippy model, I'd probably go with an 18hp or 20hp, maybe even a 15hp.