Machine shop, summit racing, jegs should all have them.
Also, are you going to overbore it? I would to make sure the bores are perfectly round. Don't forget to put new rings and bearings.
Most importantly, ask the mechanic what caused the piston failure.
98 TJ 4.7 Stroker!!! Unichip tuner, HPD30/D44, 4.56, Detroit Locker in rear axle, 3.25RC SL, 1.25BL, 1MML, 35x12.50x15, Cager Softs 15x8, XRC10 winch, Rancho 9000XL shocks with wireless remote