65 Valiant

I just kind-of inherited a 65 Valiant with a souped-up slant 6. Runs GREAT at WOT... now time to reverse engineer this thing and make it idle;-) In search of: where the heck is the engine ID? Not sure which of the two engines it has (173 or 225, I think are the options?). I'm guessing this group will help me find the answers to that an more!

-Joe