i would swap the water pump belt for a new one, also tap all the rivets in the chassie with the backside of a screwdriver , you will hear where the loose rivets are and replace them
also, i would get some welding done to the trailing arm mounting areas under the footrests, this is where a pro x cracks when its ridden hard, also put two more rivets in the footrests and 2 more rivets on the shocktower bracing, one to each side, there are two undrilled holes on the bracing, this gives the chassie some added strenght, i have my motor out also, and i had to do some welding to the hole at the bottom of the steering column, it has wallered out and the tie rode becomes loose and steering flimsy, the second thing i had to was reinforce the cage for the exhaust can, as its prone to come loose when getting some airtime...
heres a link with pic of the reinforcement to the exhaust can..
http://www.pixbox.se/pic_show_id5575288.html