Great story Steven and definitely not too long. My Mk111 Interstate number is 333555 so my bike was built just 6 later than yours. I have verification from Andover stating the bike was tested and accepted on 24/06/75 and was despatched on 27/06/75. The bike was registered in the U.K. in 1976.330549 is a Mk111 built in April 1975.
If your bike was built in April 1975 they must of been going awfully slow in the production shop as that’s less than one per week! As I understand it this was right at the latter stages of the commando builds and I guess the workforce were pretty downbeat by then knowing the end was nigh.