Glassed a 2 ft section of 5.5" LOC tubing that will serve as chute cannon for main.
Epoxied that to a 2 ft section of 29mm FG Wildman tubing that will hold main ejection charge.
Trimmed these near the bulkhead that sits closest to the front of the NC so that ejection gasses can freely pass from 29mm tube to 5.5" tube. Then heavily glassed over the area where these tubes join.
If locating the ejection charge in the 29mm tube does not result in satisfactory deployments of the main in ground tests, then plan B:
29mm tube serves as a passage for the ematch to the ejection charge placed at top of 5.5" chute canon.