The amount of flicker on the displays varies game to game for whatever reason. Like Eight Ball Deluxe does not do it nearly as much as Mr and Mrs pac and Black Pyramid. I could understand why Mr/S pac does it more with the extra display.

I don't think the resistor change happened until really late in the -35 era and well past the first 7 digit game. I'm not 100% but looking through a stack of MPUs I don't think you find the 24K resistor until the Bally MPUs started coming out with the Midway Part numbers on it. Seems like the PCB manufacturer changed around this time too.

The faster display interrupt for sure helps cut back on the 7 digit display flicker but also keep in mind that if the CPU works on updating the displays more it can slow down other things. Like in Bally chime game the fast the display interrupt runs the slower the chime bells ring out at.

All the original MPUs left in my stash are so corroded the bottom right area silk screen with the date is missing. There was numerous pcbs with 7 digit game ROMs installed with a 36k resistor but hard to say that they where not donor MPUs where ROMs got moved around and it is actually an older made PCB.

24k resistor and a 10k trimpot wired like rheostat in series with each other can give you adjustment between about 320hz and 420hz at each end of the trim pot. Thats how the NVRW replacement MPU is wired up.

Some games like Mr/Mrs pac you can enter a wierd timing setup because of when the display interrupt triggers. At around 360hz It makes the GI blinking triac oscillate and the GI gets flickery. Adjusting more towards 400hz+ clears that issue.