Domestic models of Russian equipment has no range or payload limits... the MTCR limits range to less than 300kms, but it also limits deliverable payload to 500kgs or less.
The domestic Russian models have no such limitation, however until recently orders for any domestic models have been limited by the small number of operational aircraft actually able to carry and operate the new domestic weapons, so the very small batches purchased likely had more in common with export missiles than domestic ones.
A good example is the Mig-29K... the Indians have pretty much paid for its development and production, and the Russian military are going to tack on an order for themselves, though they wont be getting the same aircraft... they will likely fit newer model engines with slightly more thrust (have heard of a 9.5 ton thrust version of the RD-33) and likely other modifications as well.
In terms of missiles like the Kalibr family of missiles the range limitations are software based, so essentially the domestic and foreign missiles are the same, but with the right software patch the range of the land attack missile goes from 280km to 2,000km...
I have also read recently that the new Kh-38 missile with options for IIR, MMW radar, semi active laser homing and GLONASS guidance options and combinations of these which has been reported to have a range of 40km for export as a replacement for the Kh-25 family and the Kh-29 has a range of 80km in the domestic version.
Another example is the RVV-BD with 200km range against an 8g target while the domestic R-37m has a range of 280km against an 8g target.
A domestic version of the Kh-59MK2 would be the Kh-59M2 or something similar.
The external engine pod would probably prevent the Kh-59M from being used in the internal weapon bay on the Backfire, but it could probably carry two missiles on each of its 4 external weapon points, though max load would probably be 7 as a datalink pod needs to be carried to communicate with the missile as it nears its target.
I would think, in terms of conventional cruise missile attack that something like the Kh-555 would be a better choice... 3,500km range would be useful.