Well...look on the barrel to see what the caliber is. If it's a 30-06, a 270, a 280, or a 25-06, then all you need is a good gunsmith and a checkbook. All of the calibers I listed are from the same basic case (the 30-06) and have the action length you'll need for the 280AI. That said, maybe that rifle only came in a long action version. Anyway, you need a long action for your project. If the barrel is in 280 Remington, then the conversion is relatively inexpensive. If it's any of the other calibers, then you have the cost of the barrel and any associated work. I'm not up to speed on what it costs these days to do that, but I'll guess and say that it's going to be over $400. There are a couple of guys on the forum that can give you up-to-date pricing and that can even do the work for you. As for what after-market barrel, I'm sure any of today's known barrel makers can give you all the quality you'll ever need.
I wonder if rebarreling a pre-64 will reduce its actual value. Still, if going to 280AI is the requirement, so be it. I sure wish I had your problem.