I don't know of anyone making them. Closest you might find is a Comp bbc, 1.7, but it's 7/16.
Scorpion makes a roller rocker with the correct 1.75 ratio and a 3/8 stud. Just make sure the stud is long enough.
I sell them for under $400.
Bob
If you use the Show Cars part mentioned above, https://show-cars.com/product/2568, make sure the spherical shape of the ball matches the pocket of the Comp Cams rocker. The balls are not a Comp Cams part. They do not make a 3/8 ball other than the ones that fit a small block rocker. Just a word of caution.
SBC balls are not the same as W motors and 6cylinders.
They used to list individual components of the rocker kits and the parts could be biught seperately.
Bob