I agree with POS!
That motor has has to come out and rebuilt. Even if you keep the stock rotating assembly. But I'd get forged pistons n rods lol. Along with morel or SLR lifters lol.
That sucks to hear but I think metal got to the other lifter and took it out if you ask me.
2001 ws6, 40k miles, Ls3 416 stroker, short block built by PER the rest by me. LPE Ls3 heads milled to 12-1 comp, FAST 102, NW 102, kooks 2", dual DMH cutouts, Magnaflow C/B, BTR cam + springs. Full UMI suspension.