If you have two .75" master cylinders, that's going to cause an issue. I have Jaguar IRS with stock calipers and Wilwood Dynalites (4x1.38" pistons) up front, my master cylinders are 3/4" on the rear and 7/8" on the front and my balance bar is set a little to the front.
It took me a long time to get my bias correct, if you are pushing your balance bar to the front, it means you don't have enough line pressure and you front cylinder is too large compared to the rear.
I think the rule of thumb is that you have between 1/4" and 1/2" cylinder size spread between front and rear because the front caliper piston area is always larger than the rear.
Piston Area Calculator | Total Brake Caliper Piston Area | BRAKE POWER
Larger master cylinder moves more fluid but has a lower line pressure, the smaller cylinder has higher pressure but moves less fluid. Because the front calipers do more work, they need higher clamping pressure.
You can either do some math or go trial and error, if you increase the size of your rear master cylinder, that should provide better balance.