OK here are the measurements with the 3 legs extended to their maximum height, and spread out to the max too.
Height to top of column - with column down - 121cm. With column extended to maximum height - 158cm.
I've got a Manfrotto 486 RC2 ball head. Add 8cm with head fitted.
For you, I think I'd swap a slight stoop when using the tripod if you can have the column lower than at full extension. You could gain a little height if the legs were not spread out so much, but not a lot before you start getting stability issues.
The supplied head is OK, but if you do swap it, you will find the 1/4" > 3/8" thread adaptor will probably stay in the head and you will have to unscrew it and fit it to the new head.
Check out the
Velbon site I think they have all the info you'll need. They make tripods with clip leg locks (5 designation) or screw leg locks (0 designation).