Rear Brake Lockup Help, Help Options

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I am running larger 4 piston Outlaw (read Willwood) calipers on the front of my v6 track car, with 911 M calipers on the rear. I installed a brake bias adjuster knob initially but my rears lockup under heavy braking no matter the adjustment. Switched to a Tilton bias adjustment with the notched rod with multiple positions and still no change. I cannot tell that there is much difference in the pressure to the rears. They will lockup no matter the position under heavy braking. They are not sticking. Not sure which direction to go from here. I am running Hawk blues front and rear. Perhaps a less aggressive rear pad? And yes the factory proportioning valve was removed.
thanks for any help guys.
LC

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I think I have identified the problem and it seems to be a weight transfer issue. If I apply the brake gradually I can press as hard as I like and no lockup till very slow speed. If I just jump on the brakes quick and hard, it locks up in a second or 2. When the nose goes down, it is the right rear that locks up. More weight on the left cause my arse is over there and no lockup. I put in larger torsion bars on the build (can't remember exact size at the moment) but I think I might have to correct spring ratios.
Running 250lb rears and I think it was a 21 or 22mm in the front. Car weighs 1900 dry. I will check the Torsion spring rate for sure on Monday.