i run a 72 duster with 513s and i love them i have had 456, 488s and i needed to 513s to get the rpm into the range i needed for the top of my power band.
the 488s went thought the traps at 6400 rpm 12.20s
i put in the 513s the best i got was 6800 rpm 11.41
that was a 340 60over motor with trw flat top pistons
mild cam
8" 5000 converter transbrake
shift at 1/2 6200 2/3 6400
like i said i love 513s
60' is 1.63 to 1.60
oh ya almost forgot sorry i am running a 29 in tall tire