gg30...I don't imagine you're doing much more than lake or bay sailing in a Citation 30 so the 1.5" scuppers should be fine. No need to go to the expense that installing 2" + hoe+ new through hulls would entail.
Why do you need a check valve as you said in your first post?
There are 2 of these drains in the cockpit, they are installed in the floor and both have a drain hoses attached that lead to through hulls above the water line. On the 1-1/2 scuppers will I need one with a ball in it? or just a plain scupper. or do all scuppers have a ball check? The cockpit floor in the Citation is kinda molded for the drains, the pic you looked at is what was installed down in a recess in the floor with a 3" strainer plate screwed over the top of it. The cockpit floor has recessed grooves molded into the floor that lead to these drains. I saw a Forespar cockpit drain fitting that was straight with a barbed end for a hose. I'll see if I can find it and attach a link to see what you think.