I've just had the 4L60e rebuilt in my G20 van, it's now running a Blueprint 383 with a multipoint RamJet 350 intake on it.
I'm also interested in reducing shift times as well, my shift times are still currently set to stock at the moment.
I've been trying to find some info about safe recommended settings before I change anything.

I've set it to shift from 1-2 at 5000 RPM, in the data log and I can see the shift solenoid activate close to 5000 RPM @ W.O.T but the actual shift doesn't go through until 5500 RPM.
I'm hoping reducing the shift times to appropriate levels will help reduce the RPM difference between commanded shift RPM and actual shift RPM and increase the life of the trans.