Honestly, if you want to go that route, I would suggest something completely different...
If part of your goal is to get hunting immediatly, I would suggest starting at shorter ranges. Get yourself a NEF Handi Rifle. Yes, I know, they are nit accurate enough to be useful beyond 200 yds or so, but they are a decent walking rifle and the quality is much higer than the price would suggest.
In the meantime, spend your money on components for your custom rifle
. As you can afford to do a stock or barrel, buy it, and put it away somewhere safe. When you have a stock, a barrel, and a good custom action, save for gunsmithing, hire a good gunsmith to put the components together, and you have your custom rifle
This seems to me a much more sensible method, as you won't be spending extra money on a donor rifle, then extra money to have the action tuned and trued, just to eventually replace that action with a custom when you can afford to do so. The resale value on the tuned donor action will be very dissapointing indeed, wheras you end up with two functioning rifles if you got the NEF first route.
I'm sure a lot of people here would vehemently disagree. The NEF is not a weapon even close to on the same scale as the wepons some of these people are used to dealing with, but as I said, it is much better than the pricetag would lead you to believe, and it will get you out shooting immediatly while you save for the eventual custom.