Since it's impossible to have a pressure difference anywhere from the master cylinder to the wheel cylinders, just plumb in a T fitting upstream of one of the front flex lines with a pressure gauge in the Tee. You'll have plenty of room there.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!