I am a 7.5D in Barrie boots and the fit is pretty much perfect. I have two 341 Harlechs and they are both UK 7E. I like the fit but I could have gone to a UK 6.5E I think. Since you have a bit of room in the 7.5D Barrie, I think you'd be okay with a 341 6.5E Harlech. But as you know, it's all a crap shoot, depending on how finicky you are about fit. Good luck.