Hi dannydebont.
I am glad to see that I am not the only one that finds the idea of a manually controlled shift register an interesting subject XD You might be interested in this thread on this topic. I went a bit overboard with my version
my version
by using a Atmega 328 IC (the Arduino chip) to control a 7 Seg display to count through each of the eight button presses on my eight LED version of this concept. Also to overcome the potential problem of any switch bounce on the clock input I used a monostable 555 timer circuit. It seems that you may have sorted out the problems you were having with your circuit so all the best and I for one would like to see a video of your project once it is all sorted out,
Pedro.