Tussi, since you didnt mention tranny I'll assume its a three speed, so if so I would put alittle more gear in it say a 488 and definetly more converter, a nine inch 4500 ought to help a bunch. Are you running slicks? Any numbers you can pick up on the 60 foot will improve the big time end substansially. Try jetting for your most mph and then go down one size. I know you said no gas, but adding a sinlge 150 shot would probaly get you in the 7'0s with no other changes, its the most bang for your buck and at that level is virtually harmless.
Goodluck, Charles