Sean, I'll PM you... Trading is frowned on, in these forums...
We worked with H&R for years to bring the barrel accessory program to Canada... We had two smiths go to the H&R plant and train in their standard of barrel fitting (truth be told, it is a simple process)... And then right when it was looking good, they were purchased by the Green Mother Ship... No chance of working with the Green Machine... Fortunately, there are a modest number of Handi Nutz kicking around and we are always playing with barrels, receivers, stocks and chambers etc... So there are some barrels around if you keep your eyes open.
With regard to barrel fitting for the H&R SB2 platform... Everything I say from this point on is "do at your own risk..."
I have been fitting H&R barrels for 30+ years... It is a relatively simple process to put together a nice swap barrel set. Fitment is usually very close, about 50% of the barrels will fit any given receiver without any fitting required... Another 30% or so will require filing or building up of the barrel lug... About 25% will require some minor stoning of the latch shelf, and about 10% will require "truing" of the barrel-to-breach face... This can be done by any noob at home with simple hand tools... The Number ONE rule is go slow and check often... Greybeards Outdoors Forum (GBO) is the best Handi resource... Scroll down to the H&R section, then click on the "Centerfire" section, the choose the FAQ's in the sticky area and read through... You can find the answer to almost any question that you might have... I am always available by PM also...
Good shooting.