Hi... I'm looking for a reliable tripod with the maximum adjustable height... something that lets me film a packed dance floor without having to find a higher grounding

I already have a 503 fluid head, so anything that can support this will be ideal

All suggestions welcome

We use a Manfrotto 351MVCF also a Vision 10.

Bobby,
if you want legs that'll get you up in the air look at the Bogen 3246. They're center column legs and with the column raised all the way up and the legs extended all the way you can get the rig 8 feet high.

A 503 head is not adequate for HD (many threads to this effect). A Sachtler Soom system will allow a high setting for the Z7, to be above people's heads, and has several other features as well.