As johnelvis said, 120 is no problem. The scratch should be no problem but if it bothers you fill it in with some black paint and a fine tipped brush. Light rays bend around either one but the scratch May introduce flare under some(not all) conditions.

$50 is an excellent price if the shutter is consistant. When you check the slow speeds there should be no hesitation just a steady zzzzp.
(hope I spelled that right)