there are 2 barrel sets available, right now there is one out on gunsinternational such as this one
which neither I nor the firing line are endorsing, just using it as an example. macon gun stocks makes new sets for 130.00 that need final fitting and ithaca gun sells parts
the new guns are built on CNC machines and don't need hand fitting and the new barrels sometimes need checked for head spacing. as I said, the cutoff point for the barrel thread design change was 855,000, after that the pretty much all interchange without gunsmithing. as with any machined part, you could run into one that does (but that happens with car parts etc),.
check out their online store. also check out eBay and gunbroker, there are any parts you could possibly need, as long as you lock that 855,000 serial nbr cutoff point into your brain