I'm with happy Feet.For fun .... unless you really like the hunt for that one period-correct widget which casts more than the whole bike when you finally find it (and absolutely no disrespect to the people who do that and love) it is a lot less stressful to grab any bike with a square-taper bottom bracket .... then pretty much any part from any era from any manufacturer will fit.
I--and many others---are partial to early rigid-frame mountain bikes like the Skate-Board King he showed above. Comfortable, durable, can haul huge loads or ride over any terrain but can also work well on pavement for anything from commuting to touring to cruising the neighborhood after dinner as the sun sets.
Pretty much anything before the mid '90s I guess ...