the bolt/stud combo is a good idea, exactly how Sard does it for their collector tanks.
btw, did u add a simple fuse since u wired it directly to the battery?
normally the current draw shouldnt be so high to melt the connector... unless at WOT for more than 10 mins? maybe u shd prepare for another pump as well. from my experience, a soon to die pump could work intermittently and draw tons of current then next moment work fine.