Hi, I did exactly the same as you ... 748 to an imported 2003 749s. I'm assuming that Ducati issues frame numbers etc in numerical order, so the lower the number the earlier the bike ? Not about to give the frame number out on the net but the frame number and engine number are under 250.
Had early problems with ECU and Clocks, and recent problems with the Battery not holding charge. All work carried out under warranty at JHP Coventry.
As for the bike itself .... AWESOME. Better than the 748 and much easier to ride fast. Love the way that it rev's so easily. After reading threads on here I think I will go up 2 teeth on the back sprocket to give it better acceleration. You will not regret the change, but, I would say go for the best model you can afford. I've never quite understood why "imports" are frowned upon .... every Ducati on the road is an import