Before I cover I wanted to drill the holes for mounting the starter and master solenoid. I laid it out on the left side of the seat base. Before drilling I spent time with this figure from the EX fuselage manual.

Seat.png

My question is how to find the vertical dimension of 5.6" and 7.5". The first go I simply measured down from the top of the seat base the appropriate distance back from the front reference. What I know is the top of the seat base is not square with the reference point, the front of the seat base. This option might be placing the most reward solenoid about 3/4" too low. The point is that the top surface of the seat base is not square with the front face where dimensions are marked from.

From photos I've seen there are lots of things are in this area so I want to get it right...not too low or too high. The tolerance tells me that there is reason for concern.

I may be overthinking this. What's the correct approach and what screw should be used?