I agree with this. My 862 heads are milled .03, ls7 lifters, and I run 3.375s. It's safer to check, but if you have to guess b/c of time issues 3.375s would be the ones to go with.

I originally guessed 7.350s b/c of the ls7 lifters and .03 mill but it turns out the ls7 lifter's seat being .05 taller than stock lifters doesn't make a change in pre-load for some reason. Any who the 7.350s were to short and made a lot of noise. Got a push rod checker the same time I ordered the 7.375s and sure enough my preload was 70-80 thousands, and they are much quieter.

 

Got 243 milled. 030", fti cam, ls7 lifters and have 7.4 PR with .095" preload

 

^^^ That might be a stretch, but hey if it is working who am I to say. I have .020 off my heads with 7.4, is good also.

 

7.4 is more than good.

 

Anybody know what the stock motors pre load range is?