I would switch it. I do know those old shimano headsets are weak and a friend of mine ovalized multiple 600 headsets and even ruined headtubes before he realized he should be using steel headsets (and also not dropping curbs and doing wheelies on vintage road frames). The issues you may run into is that the raleigh could have a 27.0 crown race seat and the talbot could be 26.4 so do yourself a favour and remove the crown races first to check this before knocking the cups out of both frames.