if you have rods, and pistons all balanced with the crank and flywheel/clutch then you should be able to take it past 7500 no problem. But the power levels will be big well before 7500rpm so you don't really need to take it past that. An Rb25 harmonic balancer is also a good idea, but as sydneykid will tell you, he uses new RB30 ones with no problems!
Andrew