While it may not *sound* like a solution, you may find that starting some "clicker" training with your scaredy cat may really help him become acclimated to human touch and contact. There are a number of people in the Yahoo cat clicker training forum (
https://groups.yahoo.com/neo/groups/cat-clicker/info) who clicker train/work with non-socialized shelter kitties (all types, not just Bengals) to help them develop a tolerance for people and eventually a connection to them--with the goal of making them more adoptable. And they report some pretty solid successes!
One shelter volunteer wrote: I've found that when working with shelter cats that are timid or fearful, targeting to your finger can actually a useful step in getting them used to having your hand near them, as a stepping stone to allowing petting. It helps them to see your hand being near them as a positive thing rather than being threatening.
Here's even a "study" on clicker training with timid shelter cats:
http://misbehaving.dk/wp-content/upload ... INAL31.pdf