The Egyptian Army bought Remington Rolling Block rifles starting in 1870.
They sold a lot of them surplus into the USA in the 1950s and 1960s before GCA 1968 banned mailorder gun sales. They were cheap because they were well worn and ammunition was old and stale when available at all. .43 Egyptian ammunition is now available but extremely expensive, $118 a box of 20 from Buffalo Arms.
The black paint is probably something similar to old fashioned stove enamel, the gun would originally have been case hardened and blued like most good quality American firearms of the day.
If anybody offers you a lot of money for it before you can disturb its handsome Egyptian paint job, SELL! Otherwise, I think cleaning it up would be good recreation. This one looks like it barely escaped being made into a lamp about 1965.