I tacked CP7 them yesterday, so it is very fresh in my head
CP3/4 beign 150mm wide, minus 25mm of SB2, there is 125mm left for CP7. So :
125mm edge on top (against CP3/4)
121mm edge in the back (against CP6)
To be sure you can do as I did :
- first you tack the "box" (CP3/4 + CP5 + CP6) on top of SB2 without CP7,
- second you tack tubes D13 and D12 in place (needs RP1 to be in place too)
You will see that CP7 naturally comes on top of D12, and there is only one way you can line it up with CP3/4 on top and CP6 in the back : you can't put it the wrong way around.
Hope this help.