2212/34 and 18A ESc sound like good choices for a 11-12oz plane. However the cells sound a bit on the large side. I guess you went for 1950's because you wanted to be sure they could source sufficient current. I'd have thought you'd be OK with something like TP1300's or even some of the 10-15C 830-850 cells.

I've found the best way (though Motocalc is good) to find the right motor/prop/cells is to read about all the other 3D planes and see what works for other people on a 3D plane of about the same weight - not just a specific model like the CAP232. There are loads of 10-12oz 3D foam designs out there!

I'm building a Southern SX2 EPP plane which is "similar" to that CAP232 and it certainly looks like the AXI 2212/34 (or sometimes /26) is the motor of choice for this size of plane while, for the smaller "shocky" kind of 6-8oz planes most are using the AXI 2208/34 (though I'm using a PJS300 and actually find that pretty good too)

Cliff