I am sorry, I am not sure what you mean by the word "taper." Do you mean nut width?
There are no specs on the website, but you could email them at
sales@dingwallguitars.com
I haven't used their customer support, but I have heard it's rather good.
The Combustions just came out last month (according to the website), but I haven't seen them in store yet, so I can't comment on it. But if you are an old school Jazz guy, you probably won't be into it. It is active, I believe you can only get they in 5 string models right now, and I am going to go out on a limb and say they are more modern then traditional.
If you want, I can give the shop that carries them a call on Monday and see if they are in yet. If so, I can run down, pick it up and give you a first hand report.
If you are into the whole jazz thing, I would go for another jazz. I haven't played the Darryl Jones, but it seems ot be what you are after style wise.
Have you played one before?