There has been a 35/30-30 for many years, and likewise the 35/30-40Krag which IIRC has a case capacity closer to the Whelan? There has been at least one recent thread about similar things, perhaps someone can link to it. I think it was also said that the 35/30-30 has a capacity similar to the 35 Rem.?
The 35/30-30 would be fairly easy and ballistics of either would be found, or extrapolated, from similar capacity/caliber rounds. For me, it would be to use the nice selection of cast bullets more than looking for ultimate velocity. The rimmed case is also a plus for me and the extractor/ejector would be 30-30, maybe the 444M for the 30-40K?
Add then the 'cool factor' of the conversion.........