You would need to figure our what crankset you want to use and then find the bottom bracket that matches it.
Scooper used something like this and just putt he bottom bracket that matched his in it. It bolts to itself through the shell and allows you to thread a regular bottom bracket into it.
Euro to American aluminum alloy Bicycle Bottom Bracket Adapter - SILVER ANODIZED | eBay
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk