Of the three items, the only one I would ever use for engine-related cleaning is naptha (Shellite), but it is no better for the purpose than petrol.
Remember that every material I have mentioned is toxic and dangerous.
I agree with Grumpy,
I was using Shellite for cleaning my 350 chev for final assembly on a rebuild last year. (it was the first time I had used it) The only positive thing I noticed was that it did not seem to hold dirt etc. in suspension quite like petrol did. However at $90 for a 20L drum at the hardware store, petrol started to look real good! It was pretty fumey too, compared to petrol, did not try it on the carby though.... I think petrol is the cheapest way to go, (even using BP Ultimate) and does an ok job for your$..
