I'm not sure how good a predictor of actual score the COMBANK average turns out to be. The number of questions is quite limited, and the subjects covered are more specific than comprehensive, meaning that if you happen to know it, you'll ace the block, and if you don't, you'll bomb it. For example, my scores on the COMBANK blocks ranged from mid 50's up to 90+. In order for this to correlate with actual test performance, there would have to be a high overlap between the subjects COMBANK tests and those tested on the COMLEX - which was not my experience.
I guess what I'm proposing is that IMHO, COMBANK is helpful for learning, but of limited use for benchmarking actual test performance. COMSAE, although, by no means perfect, is still probably the best tool for predicting scores.
Didn't write it down, but I believe my COMBANK average was between 75-80%.
Scored 700+ on both COMSAE form A and on the actual test.