LED's work fine in Baby Pacman. Both of the video hybrids (this one and Granny and the Gators) used AC voltage to drive the controlled lamps with an A phase and B phase like Bally did later on in the 6803 games. This means that these games do not have the flicker problems associated to the LED's like all the rest of the -35 and -17 MPU (and Stern MPU-100 and MPU-200) games do.
Also what this means is that each of the SCR's actually controls two lamps and bad SCR means two lamps won't light. The lamps sockets are a tight fit in Baby Pacman so I would advise installing them with the power off. If you bend a socket back and it touches another socket you will blow out an SCR.