Try this out on mame.ini You want something that look sharp and close to the real thing. Not talking about the scan lines. Just the game play on the bulb screen.
distortion -0.03 #Close to straight lines. cubic_distortion 0.05 #All 3 of the 0.05. distort_corner 0.05 round_corner 0.05 #Excite Bike change this to 12. The reason I use 5 instead of 12 because of a number get cut on some of the games. Sometimes I have to lower the number than 5. smooth_border 0.01 #Sharp the boarder.
You do not want the game screen look like a bubble screen and have blurry boarder. Go check out John's Arcade video below. You will see what I mean about that. The bulbs have more curve than the games.
I did notice that the Excite Bike on this video is showing extra graphics. The line at the bottom of the screen. In MAME it is missing or hidden. Unless I looking at the wrong sets.