The Pinch 8Z Reactor is not available at your Outpost. Please pick pone up from any major Staryards (Deimos, Stroud-Ekland, and Taiyo) as well as Akila City and Porrima. Additionally, the best place to buy Weapons is at the Red Mile on Porrima III. They sell all weapons there so it is helpful if you are trying to duplicate them into place.
Just built this and it looks great! For those on PC and don't mind using console commands. The command SetINISetting "fShipBuilderModuleOverlapTolerance:Spaceship" "-20" will allow you to skip most of the merging glitches and will let you, for example, place the reactor and the grav drive inside of each other. The only exceptions to this I could find were the landing gear and the weapons, for those you still have to do the dupe glitch. So if you don't mind using commands it just makes the build a little easier.
Thanks so much for this man! I was looking for a nice shuttle and yours is the best. Finally got it to come together. I'll be sharing your RU-vid page on my Twitter. Hopefully I can help get you more views.