I did a similar excel analysis using stock torque curves from dynos on the internet. Having your own torque curve is a big advantage since there will be variation.
The only detail that must be considered is the rpm in the next gear after the shift. That is, if you shift at 7,000 rpm in 1st, you'll be at 4,140 rpm in 2nd. The equation is shift rpm * next gear ratio/current gear ratio. (7000*2.4/4.16 =4138). Of course, the next gear rpm moves up as you're in higher gears.
The breakdown for 7,000rpm shifts is:
I'm not sure if this skews any of your shift points without sitting here and doing the math but it is something else to consider besides peak torque in the next gear....