Got a set of DP 853 pistons for sale. Never used, originally supplied by Moto Rapido in Winchester. I paid in the region of £350 for them - offers considered. 748 crank cases, including gearbox. Currently roughly assembled wirth crankshaft. Crankshaft has a knackered crank pin due to a run big end. £100. Also breaking whole engine, so other parts availible, including heads, 3 phase alternator (new in April 2012 - invoice to prove), left and right engine covers, barrels, stator, flywheel, starter clutch etc etc. PM me for details.
Not sure mate. I will have to get the heads out of the shed and check. I know that at least half of them were changed in 2010, so I owuld have thought they will be ok. PM me your email address and I'll send some photos later if I can get away from work in time.