I don't know at this point if inside reaming for 6.5 would be necessary. But, one of my long term projects is to rebarrel/rechamber one of my m/67-89 Carl Gustaf rolling blocks to 6.5x58R. If that works out well, then perhaps I would look into rebarreling a sportered Dansk Krag-Jørgensen to that caliber. But, those projects are down a ways on the list of fun things to do. Right now SBHVA and SDHunter have me all wrapped up in Husqvarna 46 and 640 rifles so the 6.5x58R project will have to wait a while.
I have seen a 6,5x58RD hunting rifle with (internal) magazine maybe 1/2 or 1 year ago, for sale on a Danish or Swedish auction website. It was a m/38 Schultz & Larsen from Otterup, the predecessor of the m/42 politiriffel.
Dear Kriggevaer, I found the rifle in the website which you had indicated (Hunters House). Its price however is prohibitive to us mere mortals.
But here is a second source, as I had remembered, an auction link to the past (not present!) catalogue 743 of Bruun & Rasmussen. The rifle is there on pdf page 10 as lot no. 11:
Schultz og Larsen, Mod. 38 fuldskæftet
riffel kal. 6,5 x 58R. Serie nr.
375, 48 cm. pibe graveret "Geværfabriken
Otterup Danmark", vingesikring
samt snelle. 36 1/2 cm. skæfte
med kindpude og pistolgreb. Ca.
165 patroner medfølger. Våbentilladelse
Riflen er færdigbygget omkring 1940 og i
meget fin stand.
One further note:
The cartridge case is rather large. Not excatly overbore yet, but that's the direction. The Finns have already reported problems with their 6,5x53R (a modified Mosin-Nagant case), and the Danish 6,5x58RD Krag is larger than that.
Therefore, the chosen short barrels of Schultz & Larsen do not at all seem sensible to me with 50 or 48 cms; the Danish army was more sensible, because they used the cartridge in their long-barrelled M 1928/33 sharpshooter's and military target rifle (trial version of the M 1928 Finskydningsgevær in 8x58RD).
My impression is that slow powders would probably be best suited with the 140 gr and 156/160 gr bullets.