If say you wanted to go the viton route , what size , lenght and wall thickness would you have to get ?

 

Just get the stuff from HighTempSilicone. It's 3.5mm, 4.0mm, 6.0mm, and 8.0mm.

Also grab some 1/8" to 1/4" nylon adapter fittings (from www.mcmaster.com) since the viton doesn't stretch quite as much on oversized nipples.

Dave