On the light-tight issue, I don't know about older cameras, but there is an issue with some cameras that have an auto wind-on mechanism which use IR light to sense the frame spacing. My Canon EOS300 35mm camera is an example, the manual states that it is not safe to use IR.
I've used Rollei IR400 in a Pentax MX, and SFX in a Canon T70, and a Yashicamat 124G.