. . . actually it works the other way. When your 3/8" AF spanner wears out, it magically becomes 10 mm. And when your 1/2" spanner wears out, it becomes 13 mm.
I used a pre injection 308 sump as the hum is reversed but the front crossmember needed notching. So I modified the sumo anyway. 253 sump is also a great start.