Use the 222 cams and single springs in the 261 head (especially if you get some mild port/port matching work done). Use the best (straightest) valves and lap them in.

I dont like the idea of putting inner 261 springs with single 222 springs. They are virtually an interference fit which I suggest is asking for trouble at high rpm.

Dont worry about the factory double springs. Their combined clamping pressure is less than earlier single springs. Go for uprated doubles if that is what you want to do.

Later 2TG(EU)'s were set up for torque at about 500 less rpm than 222's so lower spec springs. Twin springs were more about smoothness through the useable rev range.

222 cams have the same net lift as 261 cams. Advertised duration is however 256 degrees for the 222's v 244 for the 261's