I tried to lay the glue bead towards the inside edge of the BT-5 reactor bay tubes so when they were pressed onto the main tube there would be an inside fillet.
The initial curvature fitting looked better before. The edges will require some filling with CWF and Titebond M&&TG.
After shaping my crew module ended up a bit narrower than the placement lines already drawn on the tube.
To guarantee it was centered I marked a piece of paper and checked the spacing on both sides. I marked a centerline on the tube and on the crew module ends.