1. use a section of pipe to space it out from the firewall
2. lengthen the master cylinder pushrod

This is the technique used by Nissan on LHD Datsun 620 trucks.

You can use something like a VH44 remote booster instead. Doesn't need any physical connection to the pedal, just hyd pressure in, hyd pressure out and a vacuum source. Used to use one in my rally car with a valve on the vacuum line, could then turn it on or off and thus change F/R bias from boosted to none boosted. Worked well.