If I were building a kettle from sheet stock I'd design the bottom so that it had a conical terminus with a dump valve in the very bottom and run the brewery electrically using water heater elements.
Here is why:
Water heater elements are sheathed in an inconel like alloy that does not corrode ( except the SST ones which will corrode) They transfer 100% of the energy you consume into the water making for insanely fast colt to boil times and they are eminently cheap and replaceable. Use 10AWG wire to drive 'em is you use two 4500 watt elements set the electrical panel up exactly as you might a big dual element water heater.
The conical bottom and dump valve: Think "Cold Break" and "hop pellet debris." This crap settles to the bottom of a flat tank in a thick soupy mess and is just itching to get sucked up into the Dip Tube and into your fermenter. If you give it a place to go ( a cone in the bottom of the kettle) you can make the length of your dip tube to suit your experience so that you take up the bare minimum of goo while maximizing your wort recovery.
The dump valve would make it easy to evacuate it from the system and clean.
On this forum I have posted a design for a rotating dip tube you might take a look at it and see if you want to do something like that.
As to electropolishing: It's a purdy, purdy thing and produces a super clean surface, but is not going to do much more for you. It won't effectively passivate the metal as it strips molecules away irrespective of their ferritic nickel or chrome nature. If you have an electropolish rig already at your disposal, then great, but I'd not pay for the service.
Think long and hard about where you want all your ports to the pot. Weld all your ports on to the pot so that you can use cheap Buna O-rings everywhere for seals.
On my pot I have the dip tube, four ports for my integral cold water coolers, one port for incoming fluid from the MT and two for the water heater elements.