If you have a non-guaranteed transfer, as you are proposing, you should not have such a short transfer. If you are late in any way, you'll miss your connecting flight and have to buy a new ticket. The airline won't sell you a ticket with a guaranteed transfer because even they don't think you'll make it.

You'll need to clear immigration as there is no transfer facility. This can take 20 minutes or it can take 2 hours if a 747 full of Chinese just landed in front of you.

I wouldn't do any less than a 4 hour transfer.