Since everyone's asleep while I'm over here dialing in the Zippo and aiming lighter fluid ... Let me just say I don't know a dang thing about the unmodified Type I engine. I do like the mods you can make, but I think you're talking about something out of the box, no?
Tongue in cheek, here goes ... :
I've decided that the Bug engine is better for all-around ease of maintenance, parts-swapping and wheeling-dealing stuff. The parts joint can probably come up with Bug pieces in any number of combinations, and if you're a do-it-yourselfer with a wire wheel and some patience, you can make old parts look new again.
For what it's worth, I've both driven a (I guess) "built" Type I (Kelly Frazer's car has one) and a moderately well-put-together Type IV. I like Kelly's car for the highway better than mine, because it's got less oomph when you hit the pedal, and you're less likely to break stuff if you're getting your power higher in the band.
His car really seems to hit its stride at about 3500 rpms in third, and it'll hang out there all day with no real need for fourth until you hit the highway -- in my car, I'd overheat if I drove it like that.
He's also got new, aftermarket parts. I can't seem to get those reliably -- but every time I turn around, he's got some new thing hanging off his engine that he just went to the Walgreens and bought.
I'm exaggerating a little. Maybe. But it's also a better-than-stock Bug engine. It's reliable, it shouldn't puke oil, it's engineered well, it's balanced, ported, polished, blueprinted ... It's as well built as any engine in a Speedster anywhere, and he swears by it.
He also lives on a back-country road in the middle of frigging nowhere, and he'd get killed if he was grunting my engine around low in the band. For him, it's perfect.
But it doesn't matter. They're not very pretty. For me, it might as well be one of these: