looking at section 12 spec of 276781 manual for OHV singles
for 280000 vertical
cylinder cover main bearing standard=1.3795 reject = 1.383
crankshaft pto journal standard=1.3775 reject = 1.376
for 310000 vertical
cylinder cover main bearing standard=1.063 reject = 1.065 *******
crankshaft pto journal standard=1.3775 reject = 1.376
******* going to be darn hard to get that cover on the 31.
Guess what the cover spec is for a 120000 series.