This is my personal opinion on engine replacment

I do my rod every 5 litres especial in a on road engine

I do my bearings once a season

In the past i have had my onroad motors last over 35 litres of fuel

once you start geting movement on parts it will wear out the next part more
its a modified motor i would get a nother motor and rebuild this one i always have had a few motors lying around that i alternate between races meets events

i would measure the crank first up make sure its with in tolerance