Yes, the engine is in the car.
I did remove the tensioner sprocket assy & checked the jackshaft, & it turned easily, so I took up any slack there. I neglected to mention that I was installing new adjustable cam sprockets from RD.
After I reinstalled the tensioner sprocket assy, I still couldn't quite get the inlet sprocket on, so I reverted to the original sprockets and mounted both. At the moment it looks like I may need to move the inlet sprocket one tooth to take up slack between the two cam sprockets.
I wanted to use the adjustable sprockets to dial the timing marks in to match the camshaft timing more accurately after tensioning the chain, but so much for that. The adjustable sprockets are identical, with the timing mark between two teeth, unlike the originals which are half a tooth different between inlet & exhaust, as mentioned in previous forum threads.