We have a place in Lowestoft called Westgate Fastenings, they do all sorts of nuts and bolts, I could give them a ring Monday morning if you like and see if they've got an M7 x 70mm cap head bolt in stock, it's worth a shot, would save you a lot of faffing about ( I could then post it to you )

Nice thing is they'll sell you a single bolt or nut if you want !

Norm