Tripod for 67 and 400mm

I need to get a tripod to hold a mlu 67 with 400mm lens and possibly 2X TC (along with other 67 lens including 135mm macro)
Main priority is that it is stable.
Weight and cost are not really an issue.
I am trying to avoid a costly mistake, any advise out there?

redsnapper do some hefty and quality tripods for very reasonable money
link

---

My Flickr link

"Life is what happens to you while you're busy making other plans" (John Lennon)

K-5 IIs, K-7 (100,000 clicks)
My Lenses (or what's left after the arrival of the 300*)
Pentax DA*16-50 - DA35 f2.4 - A 50mm f1.7 - FA50 f1.4 - DA*300 f4
Sigma 24mm f2.8 - 70-200 f2.8 - 180mm Macro 1:2 f2.8 (ancient but spectacular)
Vivitar Series 1 105mm f2.4 Macro

I need to get a tripod to hold a mlu 67 with 400mm lens and possibly 2X TC...

I assume Gitzo 5x Systematic series.

For my purposes Gitzo 3530s with Graf Studioball is enough (645n+300mm/f4+1.4x) and sometimes Fuji 690 gsw and 690gw.

3530s is extremely stable - systematics comes without center column. It is three leg step construction - less weak tubes, less joints. Although sometimes I want bigger tripod.

My suggestion is - just buy something like this: http://www.ebay.com/itm/220956285016 and be happy for liftime!

Point is - Gitzo is easy to repair, every piece is easy to dissasemble and to buy repair kit for platic parts etc. So, these tripods on used market cost the same as new.

Thinking maybe the Gitzo G1500 with ball head quick release.