Dave, Forgot you had the Eagle heads so your valve spring choice was correct.

If your engine combo is a pre 09 block, 6.1 cam and Eagle heads, plus I don't know the thickness of your head gaskets so I would go with a custom length pushrod.

The base circle of an oem 6.1 cam as well as aftermarket cam's are smaller than an oem 5.7. The factory deck height of the Eagle head is .100" shorter than a 5.7 or 6.1 and the rockershafts of the Eagle head are spaced wider than the 5./6.1's and again, don't know the thickness of your head gasket.

The trick is figuring out the pushrod length you need without pulling the head to access the lifters to place in a makeshift solid lifter. A little home brew engineering, checker valve springs, aluminum tubing or aluminum welding rod has worked for me to get the total pushrod lengh at zero lash which then I relayed my info to Smith Bros for the correct pushrod. I can't recall the distance from the top of the lifter to the bottom of the cup, but I do remember there is .165" of lifter cup travel. I've always gone with .040"-.060" preload.