Ah, I remember those pics now
Nice set up btw
Only thing missing is quick disconnects, lol.
I would say that you should indeed be making use of all of your rad in that system the way it is, based on it having been completely purged of air. With the rad turned as it is and the heater core you have, the water will definitely fill and flow through the entire core if it's purged.
The only suggestion I might have would be instead of having the T for the air trap where it is, putting it at the output port of the rad (put a T in the short straight copper tubing coming from the output of the rad).
My thinking there being it eliminates the T and corresponding extra hose coming from inside the system to the outside, eliminates the sharp 90 degree turn at the pump, and puts the air trap at the highest point and where air is most likely to be trapped (the rad).
Here's a quicky drawing of what I mean: