I went to Home Depot and purchased a large 55 gallon storage tub to use as a rust removal container that has a lid. Then I ordered a small container of Oaxlic acid from Amazon. Here is the link on Amazon
https://www.amazon.com/FDC-Ethanedio.../dp/B01IPL7MZ6
I added half a cup of the acid to the water I put in the tub and stirred it up until it dissolved. I put in a few parts like the bench seat mounting brackets that bolt to the bottom of the frame and bolt the seat to the floor. I left them in there for a couple of days and when I took them out the rust was all gone. I read about this technique where bicycle collectors were buying old bikes that were completely rusted and taking the bike apart and using Oaxlic acid. It was amazing how all the rust went away and the paint and stickers on the bike were still there.