Look at the center head bolt on the manifold side of the engine. If it's sitting on a little round island in the casting, it's a high-compression E head. If the island extends to one or more of the capped-off injector ports, it's a low-compression F head, although that one might have been milled to raise compression somewhat.

It's not likely the stroke is anything other than stock, because changing it is very expensive. Stock bore for a B18 is 3.313", for a B20 it's 3.500".

Cam identification is usually stamped into the rear journal, on the surface that faces the flywheel. That's not easy to access. You can make a reasonable guess about what cam it is using a drop indicator and degree wheel, with which you can measure lift and duration at the lifters. If it's one of the common cams (Volvo or Isky as sold by iPd), you might be able to tell just from the valve lift, which is how far the valve moves from being fully closed to fully open. If you have calipers, try that and we'll see if that tells us anything.