Comment on the click thing - there are two bolt seatposts that make getting the exact saddle tilt easy. They can be adjusted easily on the road with no measuring tools, the new tilt ridden, then brought back to exactly where you started or say half way between. Several manufacturers. Nitto makes several. Campy has made thousands and lots are still around. Access to those bolts is a challenge but posters here can help you with solutions. I probably can still find my Campy made wrench. You might also be able to find an old SunTour. The Thompson seatposts have excellent 2-bolt clamps and will sell those clamps to framebuilders to be incorporated with posts of any setback. (I like to keep the clamps centered in the saddle rails and have two custom posts with 60mm setback to do that on bikes with steep seat tube angles.

Get the diameter dialed in first! Home Depot has calipers that will do that just fine and being digital, give you metric and English in both decimal and fractions.