The jl 1000/1 whould be a good amp to start with. To be honest,you wont even need 2 15" Avalanche from what people tell me on the ascendantaudio forum. IM gonna run my single off a 500/1 and chad the owner said it should be fine. James has his off 600 wattsrms. They are very efficiant even if you underpower them.
im gonna put mine in a full size bronco (my baby). i have enough room for about 17cf and only be at seat level, but im probably gonna do 10cf for 2 for now