I wouldn't bother with the tape...it's a one and done. You probably have what you need for a basic measurement in your house.
All you need is some string, or I use some weed eater material. And a tape measure. Use the string to make the measurements since it bends easily, then measure the length of hte string on the tape measure. There's some great YouTube tutorials...but it's pretty easy especially on typical deer like that.
Basically measure the following:
1. From the base above the eye, up and around the outside of the main beam to the tip.
2. Length of each tine, measure from the tip, to a a line where the main beam would go if the tine wasn't there.(for your 9, the left will have 4 and the right will have 3)
3. 4 mass measurements regardless of how many points the deer has they all get 4 mass measurements, which is the smallest measurement measured between the first and second points, second and third points, and then two measurements between the third point and the end of the main beam for the 4 point side. For the 5 point side, go between the last point and the tip in the middle for the 4th measurement.
4. The largest measurement between the main beams (but the measurement has to be perpendicular to the center line of the head if you want to be super accurate)
All measurements are to the nearest 8th inch. So if it's 21 and one half inch, it's marked as 21 4/8ths.
For gross score, just add up all the measurements you took. For a net score, you have to deduct any differences between the two sides. So if your G1 (brow tines) masurements were 5 on the left and 6 on the right, you would deduct 1 inch from your gross. This goes for all measurements besides the inside spread obviously. Technically that entire extra point on the left side is going to be a deduction.
I'm going to guess in the 160" gross range. He's a beaut.