We use Peterson exclusively.
All of their tanks are customizable since usually they're built to order and take 4-6 weeks to get. I prefer the bolt-together tanks rather than the giant ugly v-band clamp myself..
Often we just use a 2 gallon 6" diameter tank with the male AN's on them. The 2 gallon ones are only 19.5" tall, quite a gain over the 24" 2.5 gallon. GM recommends 10.5qt which would equate to 2.5+ gallons.
We've even ran 1.5 gallon tanks in vehicles that have big space constraints too and have not had any longevity problems. In those cases you need to run an oil pan baffle from Aviaid. It's still recommended for any LS7 car though.
http://aviaid.com/shopsite_sc/store/...s-z06-ls7.html
Peterson's LS7 breather can is pretty nice too, and doesn't take up a whole lot of space. I have several of those in stock if Peterson will be a while. No dry sump tanks though.
-Dale