3/4T power brake question

[Ackattack]

I'm upgrading my 69 GMC 3/4T (aka No Buck) with a power brake booster.

So far I have the power brake booster and master cylinder from a 72 3/4T. (Along with the proper brackets, linkage, etc.

As of right now I am not changing to front disk brakes, so should I use the 72 power disk/drum proportiong valve or the 69 manual drum/drum prop valve? I'm thinking the drum/drum prop valve.

However, it seems the brake lines coming out of the MC are flipped. I can hook up the drum/drum prop valve pretty easily by flipping it upside down, but is this going to cause me any problems?

Thanks

[Green Machine]

All you want to use is the booster itself, the master cylinder and prop valve are all wrong for drum/drum setups, you will need to reuse your old master and the distribution block (it's not a prop valve on drum/drum). There may be some length issues with the rod that pushes the MC, you will have to double check that else the brakes won't apply or be on all the time.

[69GMCLonghorn]

Yeah, if you use the drum/drum set up, all you'll have to do is THINK about hitting the brakes and the a** end will lock up on you! From what I've heard, using the disc/drum setup will help this. I used an inline proportioning valve. It worked, but the pedal always had a funky feel to it.

[Classic Heartbeat]

As of right now I am not changing to front disk brakes, so should I use the 72 power disk/drum proportiong valve or the 69 manual drum/drum prop valve? I'm thinking the drum/drum prop valve.

Just keep your truck as it is untill you swap out the front brakes. Another problem that hasn't been addressed here is that drum brakes require more fluid to operate. The disk / drum mastercylinder has a large rear reservoir to address this for the rear drums, but a small front reservoir because the front disk brakes do not require as much. Also the hard line sizes are different, so you have some fitment issues there. WES

[airdale94]

Agree with keeping it the same until you upgrade. But it's the discs that require more fluid. It's the size of the piston. The large rear portion of the reservoir goes to the front discs. The front disc lines are larger also.

I think you need some R&R Wes.