Yamaha XJ600 S/SC- D/E/F/G/H/J/K Seca II USA. 48 tooth

Yamaha XJ600 S-L,M Diversion 4DG. 46 tooth

Yamaha MT-03 5YK. 47 tooth

JT USA are listing 45, 46, 47, 48 tooth options on the JTR 855 pattern so any size should be able to be sent via overnight freight (eg, Fedex) to you asap.
Failing that, a race bike shop should be able to machine out a 5/8 x 1/4 plate chainwheel and drill holes on a 145pcd to fit your sprocket carrier, a little expensive though, but you could try a big smile........ , whoops, I meant..... .

Timpo.