Sorry I can't provide a measurement but on the subject of aftermarket units, they are often sized tight and require honing to the correct spec. My ATI is like that. Then when installing it's a good idea to apply some antiseize to prevent any metal galling. Other than installing until it bottoms out on the gear, perhaps others will have measurements. I'm at that phase too!!
69 RS Conv therapy program, Autogear M22, 8-pt cage, with a new 410! SOLD
New therapy program - 68 Coupe. Will be survivor exterior, modern underpinnings! SOLD
67 Belair with perfect floors, pinchwelds and firewall. Hmmm!