SPS, as far as I know there was no internal work done on the engine. The only thing that should affect it performance wise was the 54mm Sil Moto exhaust system. I bought mine from new and it's the only Duke I've owned so I have nothing to compare the way it runs against. Having said that, I've never really had any problems with it starting or having a lumpy tickover. I mean, it is lumpy but I thought they were all like that
As for the bikes, there were indeed 20 made, available with either the biposto seat or single seat unit. I also believe one of the bikes was a 748. Should have 5 spoke's (3 spoke were the standard at the time), exhaust, polished top yoke and stand, eer, ummm, paintjob and certificate of authenticity signed by Team Manager and current riders of Reynolds and Emmett.