Can't decide which route to go engine wise...
 

So my ls1 started making noise when I cranked it the next morning after going to the drag strip. Could be valvetrain related or a rod knock. rather than repair this engine, I've pretty much decided to put another one in there and not ruin this one. What I have now as a spare is a gen 3 aluminum 5.3. It is in very good condition. What my reservation about it is, its a gen 3 which is weaker. I wanted to turn this thing up to about 16-18 psi and let it eat. I'm not so sure this would be a good idea with this motor. I thought about putting bearings in it and gapping the rings, but I'm not sure this engine will hold up like that. Being its Christmas time, I really cant spend a ton of money on it right now. But I really need my car running. What would you do, being on a budget?

I also thought about rounding up gen 4 internals and going that route. Or doing the Summit rods and pistons, which I'd really like to do but cant really afford it right now.

I wouldn't bother swapping in a gen 3 5.3....unless you put the gen 4 guts in it like you said. I'd still see if its valvetrain related and fix what you've got.

It's most likely lifter tick. It has happened to me after a night of beating on the car. 3 different sets of lifters all did it every now and then.

I have a full set of gen 4 rods for sale. Currently pending for another member, but if that falls through, I can let you know.

Are you one to do high RPM burnouts in the water box? If so, I'm leaning toward a spun bearing. No load high RPM are especially brutal on factory bottom end hardware. Yes, some get away with it, but it's essentially Russian roulette.