Hi, Seth,
That small amount of info sent me doing some wild card searches on the old memory banks, but I think that is the rifle better known as the Portuguese Kropatschek, Model 1886. If so, the original caliber was 8x60R, the same round the Portuguese used in their older Guedes rifle. The Kropatschek rifles were designed by Alfred von Kropatschek, and made at the Austro-Hungarian armory at Steyr. They are similar to the Mauser M71 and the French Lebel rifles. The tubular magazine is a Vetterli type. The rifles are well made, and fairly effective, though made obsolete by the trend to clip loaded box magazines. There is a magazine cutoff on the right side.
The Austro-Hungarian army adopted the carbine version in 1881, and the navy adopted a later version in 1893. France used some, and even made them; the Kropatschek was not up to the new French smokeless powder cartridges, but was the basis for the French developed Lebel. Portugal adopted the Kropatschek in 1886, and later issued a smokeless powder round for it. It remained in service in some colonial areas until 1961(!). (This info from Rifles of the World, by John Walter.)
The chamber would be quite a bit too large for the .45-70, so a conversion probably involved installing a new barrel, along with some bolt face and extractor work. IMHO, more trouble than it would be worth, but it should work OK.
As to strength, I will only say that the rifle was designed for black powder and should be adequately strong for the standard .45-70 loads. As to hot smokeless powder loads, I won't give any advice or make any comments. (In other words, I don't want to be sued if you try to comb your hair and find your head missing.)
Jim
