well, if you were to use perfect world formulas, you need 5.5cc of fuel per horsepower made.
So, 235kw x 1.36 equals 319.6hp
we will work with an over the top drivetrain loss of 30% so 319.6 x 1.3 equals 415.48 hp at the engine.
so 415.48 / 4 x 5.5 equals 571cc injector.
Which works out to a 6% difference between the 540's and the formula.
Drivetrain loss is bumped up in the calcuation i used, same as the conversion from killowatts to hp, but based on those numbers, you could probably get away with a reg bumping the base fuel pressure up to 3.5-4 bar from 3 bar.
variances in engine efficiency etc will alter it, but using the formula, you will max out the injectors at around 220rwkw.