Thanks for the additional comments.  I really don't expect the initial run
to be too much of a problem, and I do plan to let the engine come up to
normal operating temp as long as all is well, and I can top off the water as
it runs.  I'm using an aftermarket RX-7 AST (air separator tank), with the
vent coming from the outlet on top of the engine on the flywheel end.
Should work OK.

Cheers,
Rusty