Go ahead and shoot the donor. Give it the best cleaning you're willing to do. Ugly lookie can be pretty shootie. You could also attack the bore with lapping compound, pour yourself some lapping jags and bring a dead one back to life, at least for a while.
I've got several 10/110 actions and Stick is pretty much correct. Cases properly FL sized in your dies with a bit (for me, not a lot, one or two fingers worth) of preload hasn't presented any issues while giving minimal case working upon firing. Brass shim stock (KS) discs are effective as verification of working headspace.
If you want a gage, then get a gage. If you trust yourself and are careful, you can try the case method. But that will be a custom headspace and factory loads might not be a good idea without careful verification.
