Andy, your 17% difference would only apply if both systems were using the same size m/c bore i.e. 1-1/32" but since his is currently 1-1/8", he has to decrease the bore size significantly more than 17%. He has to decrease his current bore size about 30% - from 1-1/8" (.99 sq") to 15/16" (.69 sq").

A $40 adjustable proportioning valve will solve the front/rear bias issue.