detritus,it might be "Custom" alright,but sounds like a pretty good deal. Getting it installed & head-spaced ought not be too bad on the ol' wallet.
if you or someone you know, that will let you rent/borrow it, has the proper headspcae gauge, and you have/can borrow a "savage barrel nut wrench" ($38.50 from SSS, brownells might have a cheaper one) you can headspace a savage in your garage.
here follows real basic overveiw instructions, NOT to be used to do the job get better one's first! You install the barrel in the receiver but do NOT put the nut on yet, then slowly run the barrel in checking with every adjustment, till there is a noticable but not excessive amount of bolt drag, then you thread on the barrel nut and tighten it down smartly. doing so takes all the "lash" threads of the barrel/receiver, and of course draws the barrel away from the bolt face that amount, and the rifle should now be properly headspaced.
no reaming, only tools needed are the gauge and the wrench.
i think Brownells sells a "caliber change" kit for the savage that consists of a barrel, a wrench, and a set of instructions (i think they expect you to rent/borrow a headspcae guage from your gunsmith)
I know of a couple of guys who've considered getting a couple of wrenches, a barrel in each caliber they like to hunt with (all with the same profile), and the headspace guages for said calibers, plus any aditonal bits they'd need for a switch over, then casing them up in sets, guage, barrel, and anything else needed for the change to THAT caliber, and a pre-zeroed scope all in the same padded storage case. and using then using these "kits" to turn a factory Savage rifle with repeatable QD scope mounts, into a switch barrel/cailber rifle. have not seen this done yet but it would be interesting to see.