A 9.5mm-piston master cylinder - like the Nissin 3/8 I put on my 'MX' bike - would give the SR a 21.1:1 ratio, or @ 78% more pad pressure than the OEM 12.7mm master cylinder.
Any Brembo, Nissin, etc. 9.5mm / .375" master cylinder w/switch should drop right in and make a huge difference, and you won't have to touch anything else.
On the rear, the 11mm master cylinder from the FX (Zero part# 25-06731) has 49mm M6 bolt spacing / rear reservoir hose / top output / clevis, and should give @ 19% more pad pressure than the SR 12mm master cylinder.
This won't be a night-and-day difference like the front master cylinder change, but it should still be very noticeable.