If its from 1974 it's a Selmer Mark VI, and, yes, it is a good one. The demand for the Mark VI became so great in the late '60s that Selmer began to have quality control issues. By '73 or '74, they got it back under control. The Mark VI was only produced through '75 in tenor and alto, although soprano and baritone Mark VIs continued until about 1980. It was superceded by the Mark VII, which simply wasn't as good of a horn. Selmer really didn't produce a horn as good as the Mark VI until the Super Action 80, Series III horns came out, and the Reference 54, which was their Mark VI reissue.
My Mark VI was a '74. Great horn until it was stolen. I've been expecting it to resurface, but it's now been 10 years and not a trace of it. I imagine 20 to 30 years from now, I'll make the news when someone finds the horn and it is returned to me.