If you get desperate. They sell a conversion kit on eBay motors to switch from a Century to a Impco LPG set up. You would have to dig deeper to see if this fits your application.
https://www.google.com/search?q=2bbr+Century+propane+car&sxsrf=ALiCzsZwpcP92HL9QG0WQUkrZgR9dnPodw:1654961399839&source=lnms&tbm=shop&sa=X&ved=2ahUKEwj2w-rS26X4AhUGl4kEHbqLAhkQ_AUoAXoECAEQAw&biw=1280&bih=631&dpr=1.25#spd=2449265306070420014
