So, time for a fitment update. As I mentioned, angle grinder time to remove a piece of sheet metal from my wreck. This really helps engine positioning, happy I cut it out
The idea was to move the engine / transmission as much forward as possible to gain clearance at the rear. Main limit is the driveshaft clearance to the suspension support U-shaped things. This is about as far as I could go:

Might be difficult to see on the picture, but height is about right and I think all moved forward by about an inch or so (will measure later). For the driveshaft it comes close, the thicker ones I will actually use might be really tight...
With that done, still a lot of clearance at the front. You can see the standard engine mount with enough clearance to the engine:
The heads will need some extra space at the top part where the bulkhead angles to the rear. Not an issue now that it is cut out, but something to keep in mind.
The cayman engine cover almost fits. On the left side it fits, on the right it fouls the crankcase ventilation elbow on the cam cover (which I was expecting and probably needs to be repositioned).
Again, difficult to see due to angle and light, but you should be able to see the breather elbow..