Update:
Good news, pump canister made it out w/o additional cutting. My initial guesstimate at the opening size was just enough.
The float sending module looks like toast, so a new one will go in.
The new pump is a Deatschwerks 255 lph unit.
And for those needing to splice wires in the tank, I offset the cuts (so the two wires can't touch each other), do a linear twist if the wires can be soldered (see note below), solder it, and then use Kynar (or the like)
PVDF or
FEP heat shrink tubing over each joint (slip tubing on 1st, etc,
McMaster, I chose PVDF )
Note: some OEM's use wire that have coated strands of copper which cannot be soldered, or just not copper wire at all. In these cases crimp the wire ends into a barrel connection, then fill heat side with solder iron, put some solder into barrel, etc. If you scrape the wire strands carefully with a razor and see copper underneath, then try and scrape some to expose some copper, crimp then solder, etc.