You might find the 'bolts' holding the coil to the firewall are actually self tapping screws with a hex head. Or they could be a 6x1 metric thread which is what the bolts holding the windscreen wiper should be. As for the bolts for the DGV weber, they'll be 5mm metric thread. It's best to get studs for this, as you can damage the thread if you're constantly doing up & undoing the bolts. Also try & get nyloc nuts, as any nut that comes off could go down the carby. It'd be best to find a fasteners supplier, take the carby along & buy some studs & nuts off him. You should be able to find someone in the yellow pages under fasteners.