Both barrels were purchased from LRH members and were reported to be unfired.I just look as it as headspace. It really doesn't matter where you set it as long as you're not stretching the brass to failure when you fireform the brass. So set it how you like, just realize you're always going to have a non standard chamber after that.
However I haven't read all your posts. Is the Shaw barrel used or new? If it is new, I'd send it back to Shaw to look at. I'd say your throat is a little short, and it would be better to have the throat cut at least .020" deeper.
I like to fix things that are out of spec, and make it right. I'm not confident that the thickness of the tape you're using is going to solve your issues 100% of the time. I know you're trying to do a budget build, but you've already doubled your costs by building two different rifles. So since you're already in this deep, I'd pay to fix the throat and keep the chamber in SAAMI spec.
I will probably set up the hunting rifle with the Shaw barrel this weekend to see what I get. I'm sure it will be well within SAAMI spec. If the fired brass looks ok, I will sight it in and see how it shoots. It doesn't have to be very accurate for a young teen to kill a deer or hog, especially since he'll be hunting where only close shots are possible. I'm more concerned about doing this safely since I'm not an experienced builder.
I'm not set up for reloading yet anyway, and I have plenty of study ahead before I start that. For now, this is strictly a factory ammo proposition, which means the Hornady 100g solution.