Where are you located? I have a Dainese Wave 1 Bap you can have for $50.Good condition.I don't do track anymore.
Ya ,it would fit.Up to you.
Contact Fawaz at Speedworx. He sells a Knox back protector with a vest. Holds in place better when taking your leathers on and off, and if you use it for street riding under textiles.
https://www.speedworxsuperbike.com/gear-and-apparel
https://www.planet-knox.com/product/track-motorcycle-vest-with-back-protector/
I have a Dainese action wave back protector new with the tags still on it if you're interested. Very similar to the other one in the post if you are interested. $80 if interested.