Try
http://www.mcmaster.com
They are a HUGE supply shop, and carry almost anything that you can think of, Literally.
Do a search for Hardware Cloth.
This is one that I found that would be awfully darn close to the original mesh in the 154 grill, without the square ridges.
If you don't like that, you can look around for all different kinds of stuff, sheets with holes, diamonds, triangles, woven rectangles, punched squares, etc. You should be able to find something that fits your liking.
I was always curious about buying something like the one pictured above, then making up a jig out of 3/4" wide boards, that you could lay the cloth in and press it, making it look like the original grill with the 3/4" wide lines. Anyway, it would be worth trying.
Bill