Is it common for LS7 lifters to have the retaining clip on the topside come out?
I had one come out on me with about 6000 miles on the whole build.

Should I just replace the one lifter and go or pull the other head in put in some morels? Car is a high compression e85 416 spinning to about 7200.

 

How much preload were they set to? (The only time I've seen what you're describing was insufficient preload.)

 

yep, sounds like lack of preload and hammered the retainer out of the lifter

 

This sucks man but at least you got it figured out. You def. have some setup issues. Dude, you need to have somebody to setup your valve train that knows what they're doing before you trash another engine!