Hello LilJohn. This is a great forum for Handi-Rifles!
If you're looking to build a set-up based on the NEF rifle,
acquaint yourself really well with NEF's "Barrel Accessory Program," their rules for what barrels they'll let you add and buy, but also the difference between the SB2 and SB1 receivers.
This last point is what's key to what barrels NEF will fit to your receiver/s you send back to them.
also ...... their site is
www.hr1871.com .
As for a case (soft or hard) to carry everything in, I'm still looking for one I'll be happy with - that doesn't cost too much!