I've got a Kevko pan on my Dart with a 360 (they make a 318/340 as well). Its not a "through the pan" deal. I am running stock K-member, stock steering, etc.
Fits very well, has a drain plug at the top of the sump for easy "set on kill".
It fits Hooker Super Comp headers, though you can't use the higher drain plug with them as a tube is to close, but the lower one obviously still works. It fits regular Hooker Comps as well.
They are not adverse to "making it your way" if you want something different.
Its got trapdoors and good baffling. Maybe not the prettiest thing on earth, but you can't beat the price.
Make sure you clean it good before putting it on. There were a couple of (tiny) pieces of metal in mine.
www.kevkoracing.com
Good Luck