I had the same problem- I stripped my cylinder down yesterday & the bore was scored. I bought a new casting & a seal kit from local Ducati $tealers- cost £46 in total. Wrecked the engine casing paintwork as well. I deffo needed a casting, but was gutted that I had to buy the seal kit that comes with a piston- the original piston looked OK. Better safe than sorry though I suppose
Apparently, the newer one fits, but it was £66 & times are hard at the moment!