CB brakes on 944 arms?

[iltis74]

I have just picked up a single pot 944 brake setup that I intend to install on a '66 bus. So far so good. However they came with alloy trailing arms. What I would like to do is put these arms on the beetle, narrow the arms from the beetle and put them on the bus. The beetle is a '70 with a CB Performance rear disc kit, and I need to know if it will be any big deal putting these brakes on the 944 arms. The bus needs narrowed arms and I've never welded aluminum. Not to mention I have no idea where to begin narrowing the alloy arms. Thanks.