Hi All -
I did a bit of digging on the TPIC6A595 based on your link and decided that I'd go with the logic N-Channel MOSFET's - still keeping the transistors and diodes - on the thought that the 74HC595 is well canvassed in Arduino forums when I come to programme the code!
Thanks all again - will come back and post photos once I've built the other 11 of these!! (first video on the left):
Cheers -
Ewen