I have a lathe that I would like to scrape to a fairly high accuracy. Does anybody know of a good place to find cast iron straight edges, which are used to mark the bearing surfaces for scraping?

I am happy to find a rough casting and hand scrape it myself.

I guess I could also just jb-weld two steel bars into a 'T' and scrape the marking surface flat. I have a surface plate.

Thanks for any advice.