This might help. The new base plate levels the base.
Okay, I've looked at these pics and the pics in your other thread about the rotating mast...and I still have questions about the slope.
Seems to me from looking at this and pics of my mast foot that:
(1) The original mast base is sloped forward slightly due to the deck being slightly sloped forward, but the mast still stands up straight (doesn't lean forward with the slope of the base).
(2) The original mast bracket (the part attached to the bottom of the mast with one bolt) sits flat on the mast base when you step the mast, but the bottom of the mast extrusion itself essentially touches that bracket all the way around (the mast doesn't seem to rest on the bolt on my mast, but on the bracket - there's an outline where the bottom of the extrusion sits).
(3) This means that the bottom of the mast extrusion has to be cut on an angle that matches the slope of the boat deck/mast base...it can't be cut straight across. I'm really curious now, because I haven't looked at this very closely until this discussion...the bottom of the mast extrusion has always been covered up by that bracket, so I never looked at it!
(4) So if the new RM bracket that goes in the mast base on the deck (the part with the vertical pivot bolt sticking up out of it) makes the old mast bracket sit flat (the part you drilled the new hole in), then it seems to me that the mast would now lean way back due to it not being a straight cut on the bottom...but you say it is sitting straight up/down...
Now I'm wondering how I ever adjusted the mast rake...in the original mast setup, the mast extrusion itself (and thus the weight and downthrust) must rest on the two bolts (the one thru the mast and the one thru the bracket) and not the mast bracket itself in order to change angles, or else one edge of the mast extrusion would not rest on the bracket as soon as you changed the angle...everything's not touching everything else here...
BAH! Someone help please!
(LOL!)
I think this is what finding41 was getting at too...and now that I've looked at all the pieces, I'm thinking the same things...don't see how you did it without it changing the angle of the mast. (not questioning that it worked for you, just trying to understand how it can work with the angles the way they are)