Some V650's were built well, most weren't. Typically ones that were Texas cars are built correctly since John H tended to not want to be sued by in-state customers....preferring to rob out of staters. So if you find one that was titled first in Texas, or ideally Houston, you probably have a good one.
As one who bought one that wasn't done well and put it back into shape, the only way to tell about the engine upgrades (basically Greg Good heads, cam, port matched intake and bigger TBs) is to put it on a dyno (unless you want to tear it down......dyno is easier). They should make between 560 and 590 RW (mine is now 585 after Greg redid the heads and had the stupid torque but no HP cam changed out); anything in that range is not only respectable for a stock-casting Gen 2 but likely an indication that Greg did the heads.
The other upgrades (other than aero kits etc) were the Penske double adjustable shocks and Unitrax half shafts. Those are easy to see. The engine is where all the money is (or isn't) so I'm afraid you'll have to dyno the thing to tell what you have or don't have with that car. If your car has the aero package be prepared for the haters, the wing and fascia polarize audiences. I like it but recognize up front that even a lot of Viper people will spit on your car ;-)
