Carb MA4-SPA

Im helping a friend with his purchased RV6A with major cooling issues.
I would like to replace the current carb with the richest available.
Does someone know which versions of the MA4- SPA 's are the richest?
I know all about drilling the jet, but feel he is in need of an overhauled carb anyway, and would just like to purchase the correct one.
Thanks

10-5009N
10-5135
10-5217
assuming you have a dynafocal 320 engine not a conical O-320.
Good Luck,
Mahlon

Thanks Mahlon!

Mahlon?

What if it is a conical?