That F-106 variant is covered by Vol. 3 No. 2 of the electronic version of Aerospace Projects Review. It's tempting to use some 1/48 biz-jet seats to flesh it out from the Monogram kit.
The one I'd be tempted to do starts with the last version of Learjet's testbed for the Longhorn wing on a Model 24 fuselage using airframe 24-218. It included a couple tip tanks as drop tanks. I would replace the built-up spar caps with machined extrusions as used on the original Swiss P-16 and include provisions for further hardpoints. I'd also pick up an aftermarket drag reduction kit, gloves on the wingroots and thickened engine pylons to reduce drag, among other things) to improve performance as well as replace the CJ610 engine with a more modern turbofan engine (upgraded Honda engine, perhaps? At one point, Teledyne Continental was looking at an engine for re-engining T-38s and F-5s with a more efficient and modern engine and this would be perfect for use here in dry form). Finally, for a proper panoramic view, I'd convert it back to the large oval windows of the Model 23 and early Model 24.
