Recently purchased my dads Tahoe with 296k miles after it had been overheating. It consumed a lot of coolant, reservior would be empty after just driving a couple miles with no visible leak other than sometimes the overflow hose would spit a small amount out. I did a combustion leak test in the cooling system and there’* definitely exhaust present.

so fast forward, I’ve pulled the heads and inspected everything with no visible cracks that I can see. I’m going to have the heads machined flat and a valve job done. But I’m wondering if these gaskets are just super worn or if they look like the heads are warped causing coolant to seep out. Or is this normal? Here are pictures, thanks for any insight.

Need to use a straight edge and see how flat the deck is or isn't. Have the machine shop check the heads for cracks. Normally the cylinder(*) that were burning coolant will be very clean. Can't really tell by the pictures.

It doesn't matter what the gaskets look like right now. Important thing is, you are taking the correct steps in resolving the issue. Get the heads milled down, replace all the gaskets. Make sure you do an overhead valve adjustment due to the machined heads now sit closer to the block.