This question depends on what you mean by 5/6.
One rod that you may like is the Sage 6110-4 XP. As a production rod, it comes with a standard fighting but. I was impressed with how it cast with a 6 weight S.A. Steelhead taper line. Blanks are available and you could use a short Spey handle on such a rod. Unfortunately, I think that a 5/6 Spey line would be too much for this rod and you should stick with a standard line.
If you are looking for an 11’ rod that will handle a 5/6 Spey line, then consider the brand new ‘Native Run’ rod from G-Loomis. It is classified as an 11’ 7 weight rod. It can be cast single handed with a standard 7 weight line, but it also does very well with a windcutter 5/6 line.
This rod is not yet available but should be by the end of November.
I’m sure that there are a few other rods that would be applicable, but these are two that I was personally impressed by.
Batson sells a 11'-6" 6/7 spey blank. Not quite what you are looking for. They are a sponsor at rodbuilding.org. 11' is an odd size - larger that most people make for a single hander and shorter than most spey/2 hand blanks.
I read some place that it is likely you'll see more and more double handers in lower weights and lengths as they are discovered for their usefulness and applicability for trout fishing - you can simply cast farther which is advantage in places and they are easier on old bodies. Spreads the work out over more of the body than slinging a rod with one arm all day. I'll be curious to see if this comes about.
CND rods makes two "Trouter" rods, one a 12 ' 6" (I think) and the other around 10 ft. Both can be cast with two hands.
I have a Snowbee Torridge 6/7 (12 ft) scandi style rod that I use on the Yak. I think two-handers (whether spey or overhead) will start appearing everywhere. I like the efficiency, long casts, and conserved energy.
I have a Bob Meiser 10'-6" 5/6 two hander. I haven't become very good as a spey caster yet, but it is a great nymphing rod. http://www.meiserflyrods.com/
Check out his site and then talk to him. He is very good at helping you choose which type of rod is best for you.
Meiser uses blanks made to his specifications that are produced for him by CTS of New Zealand for his own R.B. Meiser 2-handers.
His switch rods are made on Dan Craft FT blanks.
Gary Anderson makes an 11'3" 5/6 2-hander; but I don't know if he sells blanks. He is a custom rod builder from Oregon who has blanks made to his specifications be several different blank manufacturers.