Yea! Pretty good suggestion bro! Do you mean handstand push-ups wall assisted or not? If they are wall assisted, I'd say pike push-ups and decline push-ups are best for progressing into this exercise. Decline push-ups should be slowly higher until you reach the top(handstand push-ups). And ofcourse you need to master the handstand and handstand push-ups for handstand push-ups(non assisted). Frog stand to handstand switches is also a good progression for te handstand push-ups(non assisted). I'd also like to see that in a video! Let's hope he has the time to do so!