Powerglide TB

just tried Fairmont today 514 with glide and reverse not holding when transbrake applied . It's a protree double dump brake with both holes drilled in rev piston area. Can I install a bracket brake in this trans case ,looks like the second hole would just dead head into separator plate and not matter. . thanks for any help . I know I have a leak in reverse circuit somewhere and suspect TB plunger not sealing well and want to switch brakes. The car backs up ok when brake is applied but not able to hold forward movement.

Yes it will work but if you were installing a
pro tree double dump brake in a case that had a bracket brake you would have to drill the extra hole.