Piaggio Velofax

This little red (large wheeled) two stroke moped from the 1990s was disassembled some considerable time ago and there are two major issues to overcome. Firstly, its piston has gone missing, so its more a case of piston missing than piston broke! The barrel is spot on for size (According to the factory workshop manual we have acquired) at 38.4 mm. However both replacement pistons we have obtained measure 40mm. Nearly everyone that claims to supply pistons for it in the UK states they are 40 mm. These of course are too big to fit the bore. A French company indicates they supply the correct size but they are out of stock! We are pondering if the barrel would sustain being bored out 1.6 mm for the 40 mm piston to fit but then we do not know at present whether the shape of the two pistons and the positions of the ports are the same! The 2nd and Equally vexing problem is that one its reed valve petals has broken. This means that a large proportion of the fuel air mixture it would draw into its crankcase through it, is very likely to rush back out again as the piston (If we had one!) descends. I am struggling to find anyone who can supply a replacement and again those that have been sent did not fit. I start to wonder if this is truly a lost cause.