Hmm, I hadn't thought of it that way. The way I was thinking of it was like this.
When 1 is at TDC compression, 2 is at TDC exhaust.
At the same time, 3 is at BDC intake. and 4 is at BDC after firing.
Turning the pass cam 180 would cause it to run as the 2 cyl. But, now you have me doubting that. I can't visualize the camshaft lobes in my head very well. Next time I'm in the garage I have an engine with the timing covers off that needs a rebuild or something. Still has compression on all cyls though, so maybe I'll mess around with that and see if it's even possible to get the compression at the same time on opposing cylinders.
i think you'll end up with intake valves opening at BDC instead of TDC at least on that one side.