Estes Black Brant III, Part 1 Parts Research

I've always liked the looks of the Canadian Black Brant series.
This one was an Estes kit #1293, now OOP.

The Estes Crossfire ISX uses the same nose cone and tail cone nozzle as the Black Brant III kit.
I bought two Crossfire kits. The engine mount, nose cone / tail cone section and parachute will be used.

This kitbash is inspired by a build by JeffyJeep on YORF: HERE
The kit instructions are at oldrocketplans.com: HERE

Normally you could find the sizes of Estes body tubes at: 
Estes Custom Parts Catalog from 1974 HERE
The BT-50N tube is not listed!

JeffyJeep gave all the information I needed in his first post:
"I've collected all of the parts needed to do the build (except for the decals that should get here this week from Sandman) and I've blade cut three fin blanks from my best sheet of 1/16" Midwest basswood. 
Main BT is BT50 x 14" long. Launch lug is an LL-2B, .125" x 2.375". 
The Crossfire's engine mount tube, thrust ring, and AR-2050's are the same as what the original BBIII kit contained. I'll use an original-type "non-snelled" engine hook for the build, but I'll modernize the guts with a Kevlar shock cord leader and an extra long, elastic fabric shock cord."

Thanks Jeff! You've saved me some legwork.