Stop in for a cup of coffee

WV64Signet said

Thanks Tim.

I've set a deadline for this week to pick a course of action

Option 1 - Go to the Ramen diet and get the 273 built

Option 2 - Pull the /6 and figure out what's broke... maybe cheaper repair ... but still have to un-F$!% the transmission

Option 3 - Find a running motor someone is selling which will be a relatively simple swap with current setup

Click to expand...

What's with the deadline?
Also those options don't seem mutually exclusive.
However now that you've written them out, it looks like this to me.
Both the engine and transmission are out of commission.
Therefore no advantage in leaving them them in. Unless these are in-car fixes.
If you come across a known running replacement while you're investigating and fixing - that's a fork in the road.
In the meantime, that fork isn't there to take.

You really want to change engines and trans. Any way you slice it those are longer term projects.