Ok,
Depending on what cams you run you can do one of two things.
If your on stock ve cams you can use the det internals and slap them in the VE block and go, get you a vet headgasket and put the studs into the ve block.
Or you can get internals, if you look at my build thread, a couple pages back I posted the link to poor-boys-parts on ebay that I get all my piston and rod combos for. He doesnt carry the VE specific pistons but can get them. Or you can order the pistons from another seller and the rods from a different seller. Simple as that. Poor boys parts would give you the best all around deal. Probably around 740 shipped for an eagle rod CP VE pistons. Pistons will take 3-4 weeks to come in from what he told me.
Definitely go with the VE block, Much easier than drilling and capping the ve head, use all the ve components except for the bottom end. If your det crank is in good condition, swap the 8CW crank in along with the girdle and main bolts as long as you have a set of DE oil pans to put on there. I dont believe your DET pans will fit the VE. ACL bearings all around and good to go. If you dont have de pans laying around then just keep the 4CW crank in and ve pans.