1090-1 was a generic bally 25c machine and it had a "jackpot tower light" (aka candle), so there should be a hole more-or-less centered on the top of the cabinet for wires to go thru.
looks like you have an IGT sticker on there. IGT initially did refurbs. Is your machine still entirely EM?
the bell normally is in the upper compartment. Look for the blue (20) and red (10-2) wires in the harness going into the top - usually with plugs on the wires. One plug for the bell, one for the candle.
the ballast/starter for the door lights was on a bracket to the left of the reels.
when the machine was modified - maybe for ceasars, maybe not - anything could be added. Whatever the customer wanted. If an added topper needed a fluorescent, the ballast and starter would be mounted in the top compartment.