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Just from the video I do think I hear a very very slight noise which I imagine in person it’s easier to distinguish. It’s not severe so I really encourage you to check for pushrod straightness. As the oem pushrods aren’t very tough

That’s what happens usually bud. If they are severely bent they will be louder than that. But I’ve seen them bend bad enough to wear the pushrod hole in the top of head. Lifter lost all preload so it actually would “loft” off the cam and it was all fubar for that lifter bore lol a simple repair became a pita

If slightly bent I believe they would still be centered in the lifter and rocker cup. It may not be your issue but for the ease of checking them it helps to cross out the possibilities for diagnosis. A failed lifter sometimes causes your oil pressure gauge to flutter when oil is good and hot.

OP if you physically pushed on the rocker cups when checking them for vertical “slop” then I’d imagine you didn’t lose all of your preload and lifter SHOULD be okay. Just be certain when you get your new pushrods you verify length/preload. Ls motors lifter preload is set by pushrod length. Comp has a pushrod length checker that works okay. Also I’m glad I could help and you didn’t take the noise as normal. Get er fixed up and let it rip. Also if you measure I have a new set of chromoly tick performance 7.400s id sell you for cheap. Either way good job on being proactive on maintenance of your ride

typically they bend on a manual from the good old money shifts. Springs lose control of valves due to mechanical over-rev and the valves kiss the pistons then stuff the pushrods into the lifter. Stock pushrods are weak so they usually bend first before damage to lifter but not always. However you probably have more than one bent one. If so I do recommend getting the comp cam pushrod length checker. They aren’t much and figuring out what length you need. The 7.400s are close to stock replacement length. Also if you suspect a mechanical over-rev be sure to inspect the stock crap rockers as they like to puke needle bearings

I’m at work so it’s a bit hard for me to hear. What is your oil pressure cold/hot? Also I would not drive it like this. If it is a lifter and it turns in the bore or fails then you are very likely to be looking at some damage. It sounds like a lifter tick at idle. I don’t like that sharp squeaky knock noise when you first rev it though it may be my phone speakers lol. You’re looking at topend tear down I’d say. I don’t think it sounds really deep like a rod knock/ they chirp sometimes as well. I don’t think it’s a spun bearing. You’d probably be seeing a lot of gold stripper glitter in oil and filter if it’s a spun bearing. I’d bet you have a seized lifter wheel and if I’m actually hearing a squeak at first rev is the wheel not rolling but sliding across the cam lobe. But It’s not hard to replace lifters though if you’re a bit mechanically inclined. I’d get the morel drop ins or Johnson’s. Johnson’s are a step up. But I think morels are the only lifter who use a wire lock axle shaft at oem wheel size The rest are swedge lock and they can walk out when valvefloat occurs if ever. It’s a shame you can’t rev the motor while camera is right there. If you plan on modifying in the future. Now is the time to get a build list going if you verify heads gotta come off. If you need help I would be happy to help fellow ls owner. You MIGHT be able to verify by pulling all rockers and spinning motor several times. This SHOULD cause lifters to stick up in lifter trays. Then you can manually seat each lifter on its lobe with a pushrod. One may be very hard to seat back down but I’m just spitballing here. I’m sorry I can’t help much more than give you an estimated guess. I know how it feels. Stuff like this makes me sick to my stomach when it’s my own ride.