Measure the distance from the transom to the aft edge of the mast. The spar should stand at 90° to the mast gate (just for this measurement!), and you should include the mainsail track, as if it came all the way down where it's actually cut off now below the boom. The reading should be about 3095 millimetres. Chances are that the mast foot is farther back (smaller number) than that now. This is also part of the basic tuning; your sails may be some very old cut which may have used settings very different from the modern ones, but I still think that is the best figure to use as a starting point.
I'm not sure about this measurement that you mention, here. I get the measurement from the transom to the aft part of the mast (3095mm), but what does the main sail track have to do with the measurement? Also, am I sticking a nice, big carpenter's square on the deck to check that the mast is perpendicular?
I got my new Ronstan I beam from APS and took the old bent one out (I can't imagine how that got bent!). I now have to cut it to length and drill some new holes in the correct spots but the beam shape does fit, thankfully. A pain in the rear end to get the hardware off!
I'm still waiting for a few hardware pieces to finally get my boom vang rigged up but that should be done this week.
I will have to switch to fixing some running rigging problems on our racing boat (a flying scot) this weekend but I'm sure that I'll have a bunch more questions in the coming days regarding the 470.