Happened to me , not a nice experience. My bearings was rotten , seized and I've had to drill, mill and chisel it horribly , then remove the engine with swingarm out of the frame (together) then after long fight I cut it with angle grinder . All that after week of beating with sledge hammer , soaking in hot and cold oils , torch etc etc . Hopefully never again 
As long as you dont have bubbles from oil tank to the pump it will be fine
I've never heard of checking the engine number on Mot ... All they did ever to me was frame (VIN) number on head tube 
@oldman Agree with you , bought the big kit of ss bolts for my dtx and ended up with more than half unused and also few missing. I have contacted them and asked for the sizes that was missing and added half to the amount 
, got it up to 3 days. Now working on other project and Im happy for the spare ones 