I believe 1095 is a pretty common 'spring' steel, but it probably would benefit from by the book heat treating. Not many will identify the steels used, but I believe there are quality gunmakers that use 1095 for mainsprings. I'd also suspect a little less carbon might be easier to get the home heat treating in the ball park. Even lower carbon content than 1070 might be 5160 that has a good chance of turning up as automotive leaf spring. Options are around, I'd think start with a known steel.