Which bore 4.5 or 4.6 has less head gasket issues?

4.5

Its a gen 5 merc 93 or 94 I forget . 502 390hp merc.

If it's the light weight block you might not want to use it.

Is the 4.25 the stock crank and I would change the stroke and pistons only. to get 548?

Hey that's my saying.

The stock stroke is 4 inch.

Out of one of my 598's.Just a small leak in a header is a real bad thing.

wow and thanks for the the ED

I heard that the cometic gaskets have eliminated most head gasket issues.
What RPM's are most builders comfortable with on a 4.5 stroke 1000+ hp motor. For sustained length runs.