If you're looking to replace a 600 stock, there are not too many options...
1. McMillan. Expensive but worth it. You'll need to bed it, buy a 700 ADL triggerguard. The TG will have to be glued into the stock and either turned "backward" so that the small hole is at the rear or D&T the rear tang to the specs of the foward action screw.
2. Richard's Microfit Stocks. Laminate, Claro walnut plus a few more wood options. They are available in many shapes. I prefer the Classic 102 or the Modern Classic. You'll have to bed it, do A LOT of wood removal, and seal the stock. They inlet for the OEM or ADL TG.
3. HS Precision used to make a decent stock for the 600 but I'm not sure if they still do.
4. Reshape your present stock...
If you go with #2 or #4, look up CVMW here at the 'fire or go to Numrich Gun Parts and buy a metal replacement TG for your 600. They are well worth the $.
RH
I have the CVMW bottom metal on my .222. It is a quality piece and a huge upgrade over the factory plastic that are all broken (bad plastic in those days??). The only issue I have with the CVMW bottom metal is that the web where the screw goes through was so thick that the factory screw was too short. I couldn't find an after market one so I had to make one with a cap screw on my lathe. I think he might had changed his program to take a little more metal out of the hole. I could have done this, but didn't want to ruin to anodizing.