First question.....why? Do you just like the thought of having a car that buzzes the top end of the tach? Because if that's the case, you picked the wong engine to do it with. OHV's are made to produce torque down low and a fat power band, so don't overshoot your goals by trying to turn it into something it's not.
Anything can be done if you throw enough money at it, but I can't for the life of me understand why you would want to?
It can be done, i do research on push rod motors at the University of Central Florida and we have designed SBC and SBF motors to turn 9000+ RPM. The 302 should actually an easier motor to get up there, as the mass of the pushrods is a lot lighter due to the short deck height (compared to a 350/351). The problem with a high speed pushrod street motor that is that you are going to run it at the entire power band as you will not always be turning 7000rpm. When you design a high speed valve train for a pushrod motor, you are going to get valve loft and valve bounce - the valve bounce is what wipes your camshaft out or breaks valves. When we design these systems we focus on a particular power band and minimize the bounce while maximizing the loft. If you do not know the specifics of the valve train, under motored conditions (dynamic), you will not know where the valve train is bouncing on the camshaft nose or even over shooting the camshaft and crashing the valve into the valve seat.
I don't want to deter you from going after a project, but i just want to point out some potential problems that you may experience in your valve train.
A 7,000 rpm street car can be done easily with a hydraulic roller and still be streetable. I have a near 7,000 rpm 347, pump gas, hydro roller street car that can be driven anywhere. 8,000 rpm would be a whole other ball game.
What size cubes are you looking to use for the build?
We spin 302's to 8,000 all day in Pure Street with stock lifters you could get your stocker to spin 8 if the valves wouldn't float first it would die shortly thereafter but if thats what you want go shoot yourself in the foot
you need some good rod's, pistons, preferably with floating pins, a good harmonic balancer and one hell of an oil pump. 10psi for every 1000rpm or you're living on borrowed time. Airflow is a definate must. Heads with big ass valves,pushrod guidplates and a great induction setup. As far as a cam Crower's lvl 5 hydraulic roller or one of their solid roller cams and all their **** to match it. Price wise you might as well go Bennett Racing. www.bennettracing.com