westfw:
So it might be worth another look...
You have my vote 
And also, during the (rather fruitless) research I've done prior to opening this topic, I came across pForth, which is an open source implementation aimed at portability. It has been ported to a ton of other systems, but surprisingly not to Arduino.
I wonder if for someone (like you) who has the right set of skills, this could be an easier/ more practical way to go:
http://www.softsynth.com/pforth/
Just a thought....