Hi Inc...
If you don't mind spending a few bucks there are a few books that have the data you are looking for and more. I am an avowed X-15 geek and have amassed quite a collection of books and reference material. There are three in particular that I would recommend, particularly if you have any interest in the X-15 program beyond your model.
They are (With links to the book on Alibris.com. A great used book site. Check the prices!):
Hypersonic by Dennis R. Jenkins and Tony R. Landis
https://www.alibris.com/Hypersonic-...n-X-15-Dennis-Jenkins/book/7549613?matches=29
This one is phenomenal. The complete program from initial proposals from various companies to the proposed follow-ons. Hundreds of photos, dozens of drawings, many dimensioned. You could build your model from the info in this book alone. It also has records of every flight, pilots, carrier aircraft, mishaps, etc, etc, etc. Enough info to keep the rivet-counters happy for weeks. A big, beautiful book. For what they are asking on Alibris ($10 or so) just order it. I doubt you'll be disappointed.
X-15 Photo Scrapbook by Jenkins and Landis
https://www.alibris.com/booksearch?keyword=x-15+photo+scrapbook&mtype=B&hs.x=0&hs.y=0&hs=Submit
All of the photos and drawings that they didn't have room for in
Hypersonic. This one must be scarce, judging by the prices. Nice to have, but you will find what you need in
Hypersonic.
X-15 - The NASA Mission Reports Compiled by Apogee Books
https://www.alibris.com/booksearch?...ssion+reports&mtype=B&hs.x=0&hs.y=0&hs=Submit
This one is also a must-have if you are at all interested in the real airplane. It is what it says; the actual NASA reports. Everything from initial design ideas from the four companies who submitted proposals, flight reports, technical reports on various aspects of airplane performance and, perhaps best of all, the actual X-15 pilots manual! Lots of drawings (again, many dimensioned), of course and good photos. Surprisingly little overlap with
Hypersonic. Again, for the price just order it!
Sorry to go on so, but you came straight down my street! Hope you find it helpful. Keep us posted and don't forget the pics...
Best
Mike