I removed my intake from my 1970 454 and I noticed "deposit" build up on top of the valves (by the top I mean the side opposite the piston) on all cylinders. The motor was rebuilt 12 years ago right before I purchased the car and I have put on less than 10,000 miles on it. I'm not an engine expert, but is this normal wear or should I be concerned? I am pulling the motor to detail the engine compartment.

c,
It could be from 2 things. Oil leaking past the valve guides will get on the back of the valves and be baked on by the heat, and excess fuel will do the same thing. The newer port fuel injected ingines have the problem because the fuel is injected right at the back of the valve. Without looking at it, its hard to say if what you have is just normal buildup or a problam. Different fuels seem to have different addatives to help with the problem. The low mileage might also have something to do with it, lots of warmup time with the choke on ? Carb not adjusted quite right for low and midrange mixture, etc.