Hi Rick,
If the hull is structurally sound (transom, sole/floor, stringers) and the trailer is in good/usable condition, $2500 for the pair seems to be at least a fair - maybe better than fair - price for the pair. If major work is needed, different story.
Same for the replacement motor. Hard to say without knowing year, hours, original or rebuild, leak down/compression/lower unit pressure check results, etc. Controls from the Evinrude 175 on it in the photo should work with a 225hp 2-stroke replacement. Are rigging cost & prop included in the $2500?
As far as what it's worth, it's worth what someone will pay - especially in this market. But if...if... you know the motor is strong and the hull is sound, that's a nice rig for five grand. I bought the same hull ('86 model in a center console version) earlier this year and really like it so far. Some things could have been done differently, but the same could be said with almost any hull. That walkaround sure looks good in the photo.
Best of luck and post some more pictures. Tell us how it works out.