It's a 72 340 as designate by the "H" from HM on the front of the block.

Grab the VIN off the pan rail as there are a bunch of us, me included looking for missing 340 engines from our cars.

"37360253(might be VIN)."

Not VIN... it's the 10000 day build date and units built
3736 10/20/1791
0253 unit # that day

2631(I assume Mar 26,1971) Actually 263rd day of the 1971 year... should be Sept 20, 1971