Just thought I'd give an update as I have solved my fueling issue. During some upgrades I pulled the pump out and had a Walbro 465 on hand. Since I already had a Walbro255 in there previously, the tabs in the housing were ground down already. The W465 dropped right in, ZERO extra modification.
I purchased it along with an install kit and it had a new filter. The filter was bigger than OEM so that was the only thing that made it harder to fit into the stock canister. The housing slid together just fine.
I soldered the electrical lines + shrink wrap and was a cinch.
So, if your 255 pump fits, so does the 465.