For the outside ledge where the big ring belongs, find a larger 135 BCD used, worn-out, chainring. Such as this one: 52T 135 BCD Used Chainring.

Grind off the teeth and make your own chain guard ring. I'm just guessing about the tooth count; you will need to see what matches up best for your application. I made one for a 144 BCD Record crankset, years ago and it continues to perform well to this day.