Old cars just had a vented gas cap... nothing more than that. In your case, you could grab a small filter for a PCV system or whatever and run your hose to that. Make it as high as possible of course, should you need to ford water. Of course, when you say safely and properly, that's through a charcoal can and hooked to your intake via vacuum valve.
'91 Frankenheep YJ. 4.0, 4" BDS, Richmond 8.8, Titan 12k, 35" KM2's, rust.
'88 YJ, 4.2/4.0 head, +4½" & shackles, BFG 33's (sold)