Yes, the 835 barrel will fit on the 590 if you have an 18-1/2" barrel (not the 20" version) and will work with no modifications at all.
You should only fire 2-3/4" & 3 " shells with this set up, though.
(Technically, you CAN fire 3-1/2" shells (the chanber is in the barrel), but, the ejection port is too small and they won't eject properly....)