Dimensions for making nozzles

I am going to drill out my own nozzles but I wanted to cut out the pocket and slots for the melt filter to fit in. I was going to drill out the hole with a #51 drill (1.7mm) for ABS and then go up from there as necessary.

I'm having a lot of trouble finding the diameter of the pocket for the melt flow filter and C-clip to fit into. Has anyone cut this pocket out and know around what diameter I should cut it to? I unfortunately got rid of my old c-clamp and am running a 5-lb spool of filament today so can't check.

thanks!