[K.Wilson]

shaps,
Overheating is an issue with all FE engines in all Cobra Replicas. If you search the site you will see this is a very common topic of discussion. The 0.030 over bore will have little to no effect on cooling/overheating in a practical sense. Yes, the thinner cylinder wall will transfer heat to the coolant somewhat faster than the thicker wall but the difference would not be measurable.
Keith