4500 should be fine, you may need more spring pressure, saying "3/4 race cam" really means nothing you need to know lift, duration, overlap, lobe centers etc. Or is this the one Patricks sells? I don't know off the top of my head, but there are guidelines for spring pressures/lift/RPM. You would have to look it up. According to California Bill, if you have a good balancing job, the stock rods are supposedly good for about 5000 RPM. Don't know as I would do it with the stock rods though.
