First step to for installing landing gear is to setup the AC alignment is to level the AC in all directions followed by pulling a strill down the center line of the fuselage. This process is done by locating the tail tie-down and pulling the string to the lower edge of the firewall. The center make on the upper edge of the firewall is transfer down to the lower edge. Once the center strip is propperly located you can hange a plum bob approximately at the center of the AC with the second plum bob at the firewall. Transfer makes to the floor in order to obtain a center line point of reference. Measure out from the center line reference point to approximately 5' and draw a parrel line from CG reference line, both sides. Install a 4' straight bar to the LG spindle mount, extending forward. This will be used to adjust the spindle mount to obtain the proper "Toe-In". Hange a plum bob at the 3' mark forward from the center of the spindle mount of the straight bar. Measure the distance between the 5' reference line and the plum bob hanging down from the straight bar. The maximum Toe-In is 3/16" at the 3' mark.
Note: I would make up some type of fixture the would allow the center line/string to be "snapped" to the AC without any type of interference.
