One precaution to think about with firewall-mounted master cylinders is to reinforce the firewall sheet metal to prevent flexing during an "energetic" stop (None of us actually panic, do we?) Factory firewall mounts have a heavy brace under the dash to bolt the master cylinder onto.
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!