Yes, I believe the R20 will use the engine from the Edition 30, not the engine from the MKVI GTI. Hence if the R20 Golf is 270 standard then a remap to 300 should be possible.
Perhaps TT, if you are about, you can explain the technical and mechanical differences between the 2.0 Engine variant of that used in the Edition 30/R20 between that of the MKVI GTI?