I've been thinking about going to a hotter cam in my 64 Polara. The motor is a 426 wedge, Edlebrock Performer, 906 heads with a small amount of cleanup porting, headers, 4 spd, 3:91 gears, 800 DP Holley, Voodoo 513" lift cam, and 10.5 to 1 stock flattops. I'd like like to know how much lift I can go with stock adjustable 1.5 rockers, how much difference it will make, and how much more aggressive will it sound. I realize this is dependant on many things, but I'm just looking for general opinions here and to decide if the work and expense is worth the HP I will get out of it. Thanks guys.

this the cam you have?
http://www.lunatipower.com/Product.aspx?id=1580&gid=287
a lot of factors come in like the springs you have coil bind and so on not sure you can go much more a mo agressive street strip grind may give you a bit.
4 speed or auto if auto what stall you got?