<VV> How and where to clean cylinder barrel fins ?

[Charles Lee]

After removing all the grungy mud between the fins, I noticed that some
cylinder barrels have fins that are blocked at where the molds meet (when
forming them), but some do not.

Is it a good idea to cut through the ones that are blocked to provide
better cooling ?

I also picked up one of those diamond "pipe cleaner" drill bits for cleaning
between the fins.

Should I clean the bottoms where the fins join the barrel too, to get rid of
flaky rust or whatever's in there ?

Charlie