700R4 questions

[kens65fb]

I have some questions about a 700R4 transmission.

Ever since I got my truck, 350ci, the trans would shift late, and too snappy.

I was told that the trans should shift 1st to second at about 19 or 20 MPH.

With 3.73 gears, the RPM's are pretty high at 19 or 20 MPH.

I adjusted the cable as best I could, and the trans shifts, nicely at about 10 or 11 MPH, but I was advised that that speed was too low, and would damage the transmission.

Wat is important for the 700 R4 shifts RPM or MPH.

Also I recently installed a 2500 stall converter

Any thoughts ?