I have cut open and reworked 6 cylinder convertor and used them small bolt and all on my Super Street and Pro Bracket Cars as heavy as 3500lbs even with small 5/16 Bolts. The 6 cylinder and 318/340 converters are both 10.75
Diameter but 6 cylinder converter cover is totally rounded while others all have a flat area around 3/8 inch on top furthest from ring gear... this is probably more than you ever want to know

BTW: Was not on Drinking Binge as some guessed 12/09 to 2/10.....Major Cancer surgery instead as a lot of people already know .....Would have preferred Drinking Binge for sure.