Lol. OP forgot to mention he's swapping the engine into another chassis.
Hydroboost brakes use the pressure from the PS pump as an assist rather than vacuum.
I only know about the W123 pumps not 124s.

Pressure of course is set by the relief valve so you could screw it in a bit, but then you risk blowing out a seal or something but I think you'd be fine...

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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD