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So I've been a long time LS fan owning a several LS6 cars and now this LS1 swap 944 for the track. I've built it from the ground up and got it on the track for the first time this last Oct. Over the winter I've been making upgrades/sorting out little things. Upon removing my LS to do a clutch swap I found some unsettling indications of what I think is bearing wear. My plan is to replace the bearings and do some refresh upgrades including oil pump, front and rear cover gaskets, rear main seal, new main bearings, polish the crank and maybe rod bearings. Wasn't planning on touching the cam, cam bearings or rings (had really good compression and oil pressure despite 80k on the engine).
Anyway, two big questions:
1. Based on the photos below, in your experience does this look like I'm onto something?
2. Can I leave the pistons/rods in the engine when I remove the crank, and them have it machines and replace it without pulling the rest of the block apart? I wasn't sure what the consequences/risks of that might be.
I've wrenched a long time, but I'm new to internal engine work. Would love your thoughts and sorry if I'm actin' a noob right now. Thanks!
Looks like you had some debris in the engine. Lots of trash embedded in the bearing. I would take the engine completely apart and clean everything really well. If you just replace the bearings and slap it all back together, you're probably going to have the same problem again.
I'm the type of person that if I'm going to do it, I'm going to do it once and do it right the first time around.. just take everything apart and get that block cleaned up well. never know what lurks in the dark.. time is valuable and don't spend it on doing 1 thing twice
So I've abandoned my rationalization that I can swap out the bearings and will disassemble the block and get it cleaned and inspected by a shop. What parts can I reuse and what should i buy new? I'm hoping to assemble the everything myself once it gets cleaned up. I'm not trying to get any hp gains, just a stock reliable block. in terms of cost, I guess I'm wondering at what point it makes more sense for the machine shop to assemble the block vs. doing it myself. Since I had good compression is there any reason to replace the pistons and rings (assuming they all check out when I pull the rest of it apart)?
Lastly, any idea of a price range for the parts and machine work if I do it myself vs. have the shop give me a prepped bottom end ready for assembly?
Most shops charge $100/hr, so you can definitely save money doing it yourself. Assuming you have the proper tools and necessary mechanical aptitude. Pistons and rings are probably fine to reuse. I would upgrade to better lifters, good pushrods, and upgrade the rocker trunions, as well as install new valve springs... All of that goes a long ways in having a nice reliable rebuilt motor.
I've gone back and forth quite a bit, but where I landed was doing exactly what you mention. I just didn't see the point in dropping 3-4k into this block when I can build an LS6 or LS2 later on down the road. I really only need to see a few more seasons of track time out of this motor.
The plan as of now is to hot tank the block and heads, and then have the machine shop polish the crank, install new cam bearings and then take on the rest myself. The cylinders, pistons, rods, rod bearings and lifters all looked in really good shape, so I think the problem came from the main bearings.
I'll be replacing the following:
Main bearings
Rod bearings
Cam bearings
Lifters and guide trays
Pushrods
Rockers
Valve springs, retainers, seats and seals
Seals/gaskets top to bottom
I'll be reusing the following:
Block
Heads
Crank
Rods
Pistons
Rings
Cam
Any feedback on something I may have missed is welcome!
You are changing all the parts needed to do a cam swap except the cam, so for not much more you can gain some good power. It will require a tune, but sounds like you can just use the tuner again later on the next motor unless you go with Gen IV next.
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New LS1Tech Guy; first "rebuild" advice needed 
