DIY conical: dump valve?

I'm heading out into a brave new world and am going to attempt a DIY project to make my own conical out of a old keg. I'm still working out the details for the lid so i'm looking any suggestions for me to be able to easily clean the insides. My big question for now is what size and type of dump valve should i use? I was thinking of using the 2" tri-clamp from the top, but 2" would be overkill and I was thinking a camp/groove would be easier. Most of the commercial conicals have 1" or 1.5". Any thoughts?

-ls

 

I would go with no less than 1" valves and I would prefer butterfly valves over ball valves. I don't know what stainless butterfly valves cost and I know almost nothing about conical fermenter design, so don't rely on my opinion. IIRC, a rotating racking tube for the upper valve is a desirable feature. Large valves are desirable as the yeast can get compacted and very dense making it difficult to draw off through the smaller valves and fittings. The cone part of a conical is key to the design and IIRC it's supposed to have a 60 deg slope angle to assist the yeast in sliding down to the lower part of the cone. That's the extent of what I know about the subject.