LOM - a 1/4 clover flown the way you describe would seem to me specific to your class or type of aircraft. It wouldn't be a way to fly it (80deg nose up before rolling) in competition aerobatics, so i'm not sure how much practice or focus that gets. Is that technique something that is of focus?
The film I see it seems he starts rolling prior to your target of 80deg, you could use that same film to take a view on the rate of pitch up and height gain. Could you not?