Howdy Sleeper:
It's a cold day after Christmas here in Idaho or I'd run out to the garage, grab a spring, compress it til it binds and then measure. I promise that I will- later today. I've been down this road before, and seem to recall the coil bind doesn't become a problem until unrealistic lift heights are attained.
I am a little curious why you would choose a cam with so much duration and lift if you have no intentions of seeing the high side of 4 grand. With a cam like this you will be giving up power in the rpm range where this engine will live, say idle to about 3,500. And, a stock head cannot utilize this amount of lift. The energy that goes into any more lift than is useable is wasted and adds to wear and stress on components.
To answer you question, stock springs will be adequate as long as they are in good shape and shimmed to spec height, and as long as you don't exceed your rpm goal.
Suggestions- First ascertain whether you problem is a lifter or a cam lobe. If it is a lifter, you might be able to change it with just a head removal and the right lifter extraction tool.
If it is a cam lobe, be sure to change all lifters along with the cam and timing set.
Given your goals, I'd recommend a cam like the Comp #65-325-4, 252H. It has 425 thou lift, 252 duration, 206 @ .050". FSPP doesn't list a cam in this spec range, but Mike is very accomodating so it is worth, at least, checking with him.
Adios, David
