Phil & Mike,
I just got through with an e-mail exchange with a Volvo/MB parts dealer in the Netherlands. He owns a tractor with a B14 and one with a B16, and according to him, the Volvo gasoline engines in the tractors were identical to the ones used in the cars, and that, if he were to sell me a cam for a B18 in tractor application, it would be the same one used in the B18A Amazon. So it looks like I'll go with the A cam and the Zenith carb, unless, of course, someone has a better idea. The Norwegian data that Phil provided a link to seems to indicate that the tractor they refer to came with a B18C. (I'm going to have to spend more time with that article to puzzle my way through the Norwegian.) This suggests that they used a C cam with a matching Zenith VNN carb, whatever that is. My reasoning is that the Zenith VN36 is more readily available used from the Volvo car crowd, and because it matches the A cam, that would my best option. M.S. would be the cat's miaow, but more money than I want to spend and a bit beyond my technical know-how at this point. Besides, it would mean having to find a F.I head plus manifold, while I have two carbed heads lying around doing nothing but picking up surface rust.
I went through my culch pile (as Geopge calls it) and what I'm going to need used are the Zenith VN36 carb + manifold, a six bolt flywheel, and a bellhousing for a mechanical clutch, and a radiator. If my local Volvo recycler can't supply, eBay, here I come. The carb is going to the trickiest, so if anyone has one lying around gathering dust, I'd be interested.
Bob S.