the eb uses 100% of the pot's travel, and does have a wider physical travel than a crybaby, which uses approximately half of a standard pot's rotation (which is why almost all wahs use a non-linear taper).
pot sweep and physical travel should be thought of as independent elements, since you could have wide physical travel with narrow pot sweep and vice versa.
some people prefer wide travel -others feel it wears their foot and ankle out. mike fuller found this out after releasing the original wide travel clyde wah, later he came out with a sister version in a smaller crybaby sized case and travel.
as a piece of hardware, the ernie ball design is marvelous engineering. i love them. apparently, string replacement in these is a bitch but the smoothness the string provides ( along with the ability to utilize the full pot travel) is a feature a lot of people like. i would recommend finding the 50 bucks for a vp jr used , it would be damn hard to build something at home nearly as good without a lot of time and tools.
i have made a lot of volume pedals in crybaby cases, the upside is that a lot of players are familiar with them, most people are used to that range of travel if they have been wahing. i use a 1meg linear pot which actually goes to around 450k at toe down due to the limitation of the gear setup. if 50 dollars for a used EB pedal is too much, you may be able to find a broken crybaby for around 20 to 30. you may be able to actually reuse the wah pot. try to find one with a hotpotz2, a very durable pot, and the 100k value might work well with the active circuit you will be needing to drive the tuner out.
when you say you want a minimum volume, do you mean a separate knob on the side that sets a level that the pedal will not go below? i think the morleys have this, right?