A) Measure the distance between the valve top and the surface of the cylinder head on the spring pocket.
B) Valve top to retainer top
C) Thickness of the retainer
D) Thickness from the cylinder head to the seat locator outer recess

Installed height of the outer spring:
A-B-C-D= IH outer

E) Retainer inner spring step
F) Seat locator inner step

IH outer - E-F= Inner spring IH

Outer spring IH=34mm
Inner spring IH=29.6mm