You're close!
How many miles are on your sled? If less than 500 it may loosen up enough for you to reach your RPM target.
If not, you can:
Go to higher total force primary spring
Go with a stiffer secondary spring
Go with a lower finish angle on your helix
And of course, go with lighter fly weights (if you rode any other brand I'd say you could increase your roller size too).
Me, I'd go to a stiffer primary spring rate first and then a stiffer secondary spring to improve your backshift and give you a few more RPM up top. I think you may be able to pull those 68 gram weights!