You want the blacktop or silvertop 4AGE (JDM only).....5 valves per cyl., ITB's & 165HP. I am very much considering this for my Bugeye. Vroom!
The Geo Metro engine you're thinking of is actually a Suzuki (they made the Metro). It's the G13B, a 100 HP 1.3L twin cam engine from the '89-'94 Swift GT/GTi. They're decent engines, but have crank issues.....you need to watch the crank keyway carefully as it wallows itself out over time.
As for the Sprite in the ad.....very nice. If it were only a Bugeye.