Mpgmike slant six Duster article (allpar.com) discusses small turbo with low boost best for long stroke slant six so that it is effective in 1200-2000 rpm range.
Does vacuum actuated power brake booster work for this arrangement

Plenty of turboed FWD mopars had power brakes, with a check valve. I don't intend to run a brake booster on my car (or low boost ), but if it were me, I would put a check valve in the line.

BTW, I don't think it is really an issue with the booster working when braking, unless you are trying to use your brakes and accelerate at the same time (if your off the gas, you will have vacuum). I think the check valve is more just to keep boost from rupturing the diaphragm.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

The power brakes should still work in this arrangement, just make sure the 1 way chack valve is functional. If things are still kinda weak, you can add one of those vacuum resevoir cans. I have that exact setup on my Polara, except it's a centrifigually supercharged v8 instead of a turboed /6.

On A-Bodies, I really, really like a manual disk setup. I don't know how ambitious you are, but a turbo could be a good excuse to go to that arrangement.

Thanks for the info on inspecting the check valve...I also have a booster vacuum tank on my 65 Dart. The effort using front disks (I'm presently adding) will determine if I need to stick to power brakes.

Does this lower vacuum also effect the distributor advance unit

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

The turbo wont reduce the usable vacuum, unless you add a radical cam at the same time. The turbo only adds pressure when it is spooled up. You wont see any affects to vacuum operated units just by adding a turbo, unless you don't protect them from seeing boost.

In regards to the distributor, I would add a check valve there also, but again, it's only to keep boost out, not help with vacuum.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

I ran a vacuum booster on my Grand National after having too many problems with the original Powermaster system (an electric hydraulic system). It seemed like a great idea but never worked right and was not safe. The factory recall did not fix it. The junkyard booster I got worked fine and is a very common modification on those cars. I at first installed an extra vacuum cannister with it so I had two check valves, the one on the booster and one on the can. I later removed the can and it was still fine. As pointed out, many factory turbo cars use a normal vacuum booster. I would avoid the check valves in the blister packs at the parts store and get a factory part. The chinese ones are junk. You should use some sort of hose clamps too. My self I would swap to a manual master cylinder. It is just so easy and works great on these cars, nice and clean too. Oh, you cannot run a check valve in the vacuum advance line. It will advance and stay if you do. The boost won't hurt it.

Hmm...

I hadn't thought about that. I would guess it would still work if you had a way to "relieve" the vacuum.

I don't expect to have vacuum advance on mine, so I haven't research it.

Good point.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

I got rid of the vacuum advance distributor on my forced induction car. Seemed like more trouble than it was worth to me - I didn't really notice much of a gas mileage decrease (when you're only getting 13mpg anyway...)

You could always try it w/o a check valve on the vacuum advance and see if it blew out the diaphram - just be very conscious of what you're doing. Boost + detonation/preignition is a real efficient way to destroy pistons.

If you want to do vacuum advance, I'd think the best route would be to have both a one-way valve, and a way to vent the vacuum canister when the check valve closes.

When I was running a carbureted turbo setup, I used a vacuum advance and didn't blow the diaphragm. My current setup uses computer-controlled timing that behaves as if it has a vacuum advance, but it also retards timing under boost at the same rate it advances the timing under vacuum.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

to awnser the original question.... you'll be fine using power brakes... when under boost, it only takes 1 sec off the throttle to get vacuum back... heck, i can still use my pb's when boosting. (tested for emergency)