I am taking my cummins motor out of the dodge soon to put into an 84 chevy. I am going to buy headstuds before I put the motor onto the frame and I was wondering if I should do some 60 pound valvesprings while I was at it. What will the valvesprings do? Make the valves close quicker? Will I feel a difference in power?

 

First question would be what power levels are you looking at, neither required for any where near stock levels
You will not feel any difference in power with springs and the valves can only close as fast as the cam profile permits. Heavy springs areused if you are going to use an exhaust brake or changing the govenor spring to rev thne engine higher
Search is your next best friend, there are heaps of threads covering what you asked. Go check the sticky's and performance section for the 5.9
Cheers Steve