Ok I'll see what the smallest 100v caps are. The only bit I'm stuck with is the high power resistors. The Original dosnt show a rating and the similar Burger design shows the bootstraps as 2 watt and the sense res as 5 watt! dose this seem right?

The other problem is that although the original board used this configuration the motors are only 2 amp per phase so I will need to lower these values to set a temporary 2 amp max current. This shouldnt affect the pcb layout tho. maybe just use a large res mounted vertically?