Well The previous owner definitely wired the voltage regulator wrong. To my knowledge, I’ve rewired it correctly now and we will see if there is any changes tomorrow because it’s currently too late to start the bike right now.. I also invested in a new multimeter because mine was a little janky and old. The field coil checked out good but when I test the stator, all yellow wires read 0 ohms. Does this possibly mean my stator is bad? I have a spare stator and it reads the same.
Most digital meters with a 10-ohm range will read the stator OK, but if they don't, it may not have enough resolution. They are 0.7 ohms each phase. Also, low-ohm ranges on digital ohmmeters take about 6 seconds to settle to the final reading, so hang onto the wires for a while when reading these low-resistance windings.
Your color understanding is correct. I don't know if or how is was mis-wired - possibly even before you owned it - meaning - maybe it's bad now? The fact that the sales lising on ebay omits the CB750A is either an oversight, or reflects a limitation of that regulator. I see other regulators that include many of the models listed also include the CB750A, so maybe it'll work, and maybe it won't.
What kind of meter do you have? Most have a "zero-ing" function - meaning you can either set to zero by touching the leads together and adjusting the setting; and others will reset to zero with a button push (with the wires together). As Hondaman said, the expected resistance may be too low for your meter to read accurately.
At this point - which field coil is installed? A CB750A coil, or another?
If I were in your shoes, I'd be buying a CB750A specific rr. I know it's expensive, but it will likely be quality, and be the right part. Saving $$ on a part, sometimes, ends up wasting time and money.