UPDATE 1-BHP, Rio may revise or postpone iron ore JV -report

* Delay allows time for Australia tax review-Wall St Journal * BHP, Rio may also wait for iron ore price to fall-report SYDNEY/LONDON, Sept 30 (Reuters) - BHP Billiton (BHP.AX: Quote, Profile, Research, Stock Buzz) (BLT.L: Quote, Profile, Research, Stock...