I run a MAP system. The load question is very simple to answer. Think of it this way. With your throttle at 50 percent open or 90 percent open how much change in vacuum (load) will there really be? The answer is virtually non. For the same reason your maps only go to %54 on the TPS because anything after this is will look at as WOT. My MAP system is the same as that anything after about 50 percent throttle the amount of vacuum change is negligible so in effect it goes to 0 vacuum or 100% load on my scale after about 50 percent throtal.
How I messed the maps up is that when my car is at idle it is at the upper left corner of my map. For you it is in the lower left combine this with the reversal of the scales (RPM versus load) and I screwed it up. What I did was to invert the columns vertically
You can compare these to as they are the "same map" just that the second one is the correct version the first one is the one I made that I interpolated incorrectly.
THe map I inverted the #'s in the vertical axis (runs ok actually)
Correct map (runs extremely well with the little hesitation I noted previously)