I have contempra tub and shower combination trim and related valve. Want to increase height of shower head when I install and wanted to know max dimensions or any principles that I must honor when installing rough-in.

Although your local plumbing codes may vary, rough in numbers are pretty flexible. Some handicap access wheelchair showers have low fittings and I have seen showers with ceiling mounted heads. Placement of mixing valves and shower heads is pretty much your choice. In my MBR shower, the mixer is at 4 ft, the shower head at 7 ft, ceilings at 9 ft.