The “popular head swap”? I’m pretty sure he means engine swap …

“948 willys overland jeep
fuel: gas
title status: clean
transmission: manual
this truck I recently found in a garage in the marina district of San Francisco. it had not ran since 1995. so I guess you could call it a barn find. I trailered it home, flushed out the gas tank, replaced the fuel lines, dropped a new 6volt battery in it, replaced the coil and adjusted the points. it fired first try after purging the empty fuel system. completely rust free, it has the popular head swap which puts the carburetor through the hood, that is the only mod. this won’t last long.”

https://portland.craigslist.org/clc/cto/d/1948-willys-jeep-cj2a/6269039003.html