Best to go with one that's the same size. That's the advantage you have now. When I built my carbs I used a pair of old Carter strip-kits which covered all of them. I started with a box of old carbs and matched venturis and jets and rods and made a pair that would work. I'm sure your carbs come complete already.
Mine worked good. Hauled the mail and still pulled down good mileage. I built my own linkage to hook them together and set up the front carb as my primary and the back carb as my secondary that opened after the front was about 2/3 rd's open. Even built my own air cleaners. Big oval one and also 2 smaller oval ones that I turned sideways. Used aluminum flat sheets. Lots of fun.
Only problem I had was fuel pressure set up and float levels as I lived at 3500 feet above sea level.
Good luck with yours.