ground strap

So I installed the new gas tank that the previous owner included in the deal with the '75 Scamp I bought last Fall. I now need a ground strap. I ordered one but it was the short one (3 1/2") - I need the longer one. I rigged 1/2 a speaker wire with allegator clips for a temp. Any ideas on what to use for a more permanent ground? Or do you have an old longer ground strap you wanna get rid of?