But the more effort you put into to it to get the surface right the better the finished result.
I'm sure you won't have to much trouble sourcing a new ( or recon ) engine for it.
Thinking of ways to save you money, do you know of anyone with a Ramp / Pit that could take it out? you could then take it yourself to B/Burn, if the unit is complete, they will strip re bore / replace it all ready for your Mechanic to refit, that way you will have the Original unit & know it's condition.