I had the zx14 24.5mm piston and I tell you there is no room for milling or anything as the valve pockets are very deep into the skirt as they are.

Long rod would make the rods heavier and cam timing complicated to dial in properly
as the 122mm short rods are already good enough for 1.75 rod ratios

Now if you can fit that zx head on the a12 block it would be more beneficial or
use Simons blackhawk a12 headed beat for 9000-10000rpm true 220hp potential without
worrying about pushrods and valves flying apart or rebuilds every race.