My front tires bounce went I drive between 70 mph & 75 mph, I have had my tires spin balanced ,& I have put new shocks on the front ,but I still experience tire bouncing

If they have been spin balanced properly, then the wheels and/or tires are out of round or you have a bent rim. The right way to check this is to use a dial indicator and measure the runout of the tire and the rim. A good tire shop should have the equipment to measure this. There is always some radial runout (difference in distance between the center of rotation and the outer surface, both on the tire and on the wheel). When the tires are mounted on the rims, If the high spots of the tires happen to be aligned with the high spots of the rims, this makes the total runout worse. If the high spots of the tires are aligned with the low spots of the rims, the total runout is better. There is a limit on how much runout is acceptable to give a smooth ride. The tire shop should also measure lateral runout, which is the side-to-side variation in the wheel as it spins, or "wobble". If excessive, this would be a sign of a bent rim. Also, with the vehicle jacked up so the weight is off the wheels, you should check for any looseness in the suspension and bearings, which can also cause vibration.