Replaced fuel filler valve, what next?

[Hasdrubal]

Hello all, I noticed for the last few months that my car was becoming reluctant to fill the tank, seemed like I was getting to 3/4 on the gauge at best. Some searching here led me to think the fuel filler valve was the most likely cause, and I replaced it a few days ago.

Got the car up to a bit over 7/8ths on the gauge the next fill up, but that was topping off enough to spill a bit. I don't generally do the topping off bit, not sure how bad it actually is for the charcoal canister but definitely don't like the spills. Unfortunately this means I'm not actually sure if it was a bad valve or just a bad seal on the fuel nozzle, but it doesn't happen with the other cars I drive, and I figured it wasn't a bad choice to replace the valve.

Is there another part likely to cause incomplete filling? I don't know what to search for, all the terms and phrases I came up with just pointed back to the same valve. Kind of hoping it's not a replacement sending unit as the next step.