I had 1993 PGT and I think you should go with the KLZ motor it would be alot easier than doing an engine swap. The KLZ is the japanese verse of the 2.5 probe motor a is a direct drop in. Cruise some of the probe sites, they will have alot more info.
If my memory serves correct I think it got 200hp out of the box.

try this link.. http://www.naplesnews.com/staff/fortier/suprprobe/Welcome.html