recently bought a 1987 indy 600 improved stock sled. the last time it was ran it was used in 660ft. drags 2 years ago. i would like to run it in speedruns, 1000ft, ice track. motor was proffesionaly built. runs 9500 rpm,s, stock gears 21-35. the guy i got it from said i should change the helix. there is a straight 34 in it now. someone mentioned a straight 40 or a 44-40. any ideas on a good helix and maybe a spring to go with?????