Looking at set of heads...
 

Looking at a set of stock 243 castings ls6 heads. Seller said this, "They are used and have some minor wear on the spring pads, slight indention from locators. This is the only thing that I see that may need corrected in order to be used on a running engine."

Would this be a big problem to fix? What kind of $ or parts would be needed to fix this problem?

Get some photo's, hard to tell from the description. Also, not sure why the locators would be like that unless he isn't describing it correctly. There are so many really nice sets out there, I would pass if you are at all concerned. I picked up a set for a friend recently with 7K miles for $450. They were practically new.

http://i17.ebayimg.com/04/i/000/d4/ec/5bf3_1.JPG
http://i19.ebayimg.com/03/i/000/d4/ec/7361_1.JPG
http://i9.ebayimg.com/03/i/000/d4/ec/7f42_1.JPG

price is right at about $250

I would take these pictures to a Cylinder Head shop and get an opinion!

I do not thnk it will be an issue because they can either use a spacer and a spring accordingly or they might be good and just need a new set of springs!

Regardless though I would get a new set of heavy duty springs!

It looks as if there was a large lift cam in there and no new springs to help and it kept binding the spring - Just a thought as to why they have the groove or slight indent!

Thanks,Matt

How does that price compare to a new set of LS2 heads or bare castings? If you machine down that groove to flatten, you will need to build it back up with shims or another means. You may also want to get measurements on the valve guides.