I just watched GEISHA BOY.
Not surprisingly, the overall look and quality is identical to ROCK-A-BYE BABY. Considering they are a related pair of 1958 VistaVision films, that's to be expected. So my earlier review applies to this film with a few additional notes.
GEISHA BOY doesn't have any issue with that wonky flashing white line during the opening credits. However, there is a briefly distracting event in the scene where the Jerry Lewis character meets the father played by Sessue Hayakawa. There is an odd and noticeable stobing color shift where the color keeps changing for several seconds. It's not a lengthy issue but I mention here in the interest of full disclosure.
I rate the overall audio/video presentation very high.
I noticed a couple of things of interest. At one point, Suzanne Pleshette clearly flubs a line but corrects herself and continues on*. It was only one word and it didn't bother me at all but I imagine that, today, they probably would have done ten takes on that scene.
Another thing I noticed was that, in order to indicate the Military Air Transport Service (MATS) plane travelling in different directions, they simply flipped the image. That might have worked were it not for the huge "U.S. AIR FORCE" written on the side in giant black letters...which appears BACKWARDS in some scenes

.
Very enjoyable film and a worthwhile buy for fans of early Jerry Lewis. I, like many others, lost my taste for Lewis material in later years but I still enjoy his first few solo films.
*The flubbed line occurs when Suzanne Pleshette sits down next to Jerry Lewis on the MATS plane. The line should be "I've never met a magician before". She momentarily stumbles on the word "met" before catching herself, reading the line as :
"I've never read...met a magician before".