Look for architectural salvage firms near you. You can email photos to them.

Be careful to replace that radiator with a new piece of equipment that will offer similar BTU output to the piece you're removing. Otherwise the room could be inadequately heated and cold as a result. Your HVAC or plumbing contractor should help you with sizing and available choices.

Yes, be really careful. Our kitchen was seriously under gunned with the baseboard heating we formerly had. We did the opposite of what you are doing. We went to a salvage place and found a lovely old radiator (very narrow like I had never seen before) and tore out the modern baseboard heat. The kitchen is much warmer now. Our HVAC contractor did calculations for us that determined what size radiator we needed.

I suggest you look on Craigslist and Facebook Marketplace to find the asking price for similar radiators. There are shops that restore and sell old radiators. See if there is one nearby. Worst case scenario you can sell it to a recycler but you probably won't get much for it.

Look at the Myson toe kick heater. They have the best product out there. We took out a 6 ft cast iron radiator this past fall in our kitchen remodel. I called Myson directly and got their advice as far as sizing. You purchase the heater and the extra components from Home Depot. It is very inexpensive !! Don't let that deter you. It is amazing ! Quiet and very efficient. I love that thing and am so glad we did it. Your plumber will hook up the " in/out " to it and when your boiler kicks on and the temp of the water reaches the setting...I think 90 degrees the blower comes on. Remarkable quality for the price. c