The stock bolt and this custom bolt both show the same contact wear in my Tikka 308. I used a marker to determine if the receiver is good enough to build a 28 Nosler from. Would you build a semi-custom based on this imperfect receiver or are most Tikka receivers similar to this?
It’s typical that the 9-12 top lug shows more wear than the 3-6 bottom lug does as the bolt sags down with gravity camming on the top more. It’s under firing that it evens out but that doesn’t show much wear as it’s not moving anywhere. That’s why you really should measure it to be sure they are actually even.
Did you have the little screw in spring loaded jig to put tension on the bolt when you did the contact test?
I'd look for 80% contact on both if I was building something. Pretty simple to true it up, or you could even lap it into 80 percent contact on both sides. If you have a lathe and true it up, you can true up the receiver bolt lug abutments and bolt face too. But obviously then you're adjusting the headspace and "pre-fit" barrels won't headspace right without actually fitting them to the action.