I have just spoken to a friend who restored a -56 Inter last year. Yes, it has a valve lifter. According to him, there is a hole going into the left side of the cambox. The lifter pushes down the exhaust rocker. On the left side of the cambox is a lever connected to the cable. Everything is clearly visible with the tank off. He also said that the axle is excentric and can only be fitted from one side. Hope this helps.
Hopefully I got it right. A bit hard getting it right over phone, without actually seeing it.
He was not sure if the wire nipple should go to the lever or attached to the engine or the head steady, if there was a head steady. I saw the bike running last summer and think he had made a head steady to it.