One of my books show starting charge 34.0 and max charge 36.5 for 4895 and a 90gr bullet.
I establish overall length by making a dummy round (no pwdr/primer). Start with the bullet seated pretty far out. Mark the bullet up with a sharpie. Attempt to chamber it. Continue seating the bullet deeper until it chambers, with just a slight marking on the bullet from the rifling. You will probably get the dummy stuck a few times before you get the length right, so have a cleaning rod handy to pop it out between length changes. Record the length and proceed to work up your powder charge.