I would not use a 2wd block, the 4wd one is strengthened due to the diff etc being bolted to it, and it is just a much stiffer block.
I think you can use a 2wd block though.
1 litre of oil in 1000k's(600miles) is not bad, mine uses 1/2 litre every 150miles!!
I know mine is rings gone, still making good power though!!
tabetha