Should not be a problem with that head and height. No air will be sucked
in.

You should get a decent shower from that head. Just make sure there are
no
restriction at the top and bottom of the hose first. They may have put
flow
regulators in the hot and cold tails to the mixer too. You have approx
0.7
which should give a decent shower. The height from the shower head to the
tanks water line is what you measure.

certainly should - I get a decent shower with around 6' head (although I did
need to get a large bore "for gravity systems" shower hose, the old one was
for electric and was quite narrow giving a very poor flow rate)