I've had problems with the stops sold in pbr's "non linear" kit having a weak hold (flipper bat bounces when the ball hits it in the hold position).
Use the "bly-a613-127" coil stops. They're drop in replacements and work great. I've done probably 10 bally conversions with these parts with great results.
Parts needs for L and R flippers -
Left pawl: A-3711-3
Right Pawl: A-3711-2
(2) small E clips - HDW-CRING316
(2) Springs: SP-200-212
(2) Plunger & link assembly: A-3714-3
(2) Coil stops - bly-a613-127