Thanks for the report. Congratulations.

Forgive my rant, below, on "steam vented head" headscratch

The term "steam vents", presumably referring to the six additional coolant passages between the siamesed cylinders in 261 blocks/heads, is a misnomer introduced by Jim Carter (most likely) and promulgated because it sounds neat?

If there is steam in the block or head, something is probably wrong with the engine's cooling system. All parts/aspects of a cooling system are designed to prevent boiling (over-hating): all parts of the design - not just the extra passages needed to properly cool a 261.