So I’ve owned my 64 valiant since August 1968.

Looks like an awesome update to me! I didn't see an entrance to a rabbit hole anywhere....lol. You've planned well, so you should have little, if any trouble. Will you be able to run the engine on a dyno to sort it out before you install it in the car? That might make it easier to fix something like a leak if it occurred. Like you, I'm a few years older than my cars. While they're just as much fun as they were when we were young, it ain't nearly as easy as it was when we were kids!

:thumbsup::thumbsup: