Hi Ronnie,
I also own a Honda Prelude the exact same model as yours - love the car heaps. An absolute pleasure to own and drive!
Am also retired auto mechanic, seems like you may have a problem with that low piston, could be anything from a blown crank big end bearing to a broken piston pin. Without more info, not easy to diagnose.
A few questions needing answers -
Did the motor ever get overheated or run out of oil or stop quickly?
Did you hear any unusual knocks or rattles from the engine when it last ran?
Was the head gasket actually blown between 2 & 3?
If you send me your email address I can forward a copy of the workshop manual for your car!
Hope this helps...
Cheers,
ausmec101