Well not a monumental failure, but not flyable. My intake window is not big enough. I purposely made the window and the crank center slightly undersized. That sounded reasonable, because I think it broke originally due to how thin the crank was. But, doesn't really draw fuel as well. Once I got fuel to it to lubricate the crank, it feels normal. Nice and loose. But it runs. So there's hope for the next one.
It sounded like you could pull a small, relaxed, sport free-flight with that, if you could get it to hold a needle setting. Something designed for a 1950's 049, or a TD 020.
Flying engine first, fire-breather second...
You could put in a smaller venturi to match your smaller crank -- they'd still be undersized for the transfer ports (assuming everything was nicely balanced), but you'd have better needle response, and maybe something that would run. You could just do a quick & dirty insert with a piece of wood, for a test.
Did you check the intake timing? A smaller window would reduce the intake time, which up to some point (that I don't know, but I'll bet it depends on the porting) should make for easier starting and lower-speed tractability -- but if you put it too far over one way or another it'd mess things up. It would be good to check your work on that. An A/B comparison of the old and new intake timing may help you figure things out (or you could post it, we seem to have experienced engine modifiers here).
You could modify the crank easily enough. You could open up the window with a Dreaded Dremel Tool, or you could figure out a work holder for it in your mill. Opening up the hole would only take chucking the crank in a 3-jaw.