I found that with a genuine Yamaha brake cable, fitting the mount offset towards the front made for a nicer cable routing than with it the other way. It may be different with a Venhill cable because they have a straight ferrule where the Yamaha cable has the curved ferrule.
I have noticed that in photos taken in the late 1970s, TYs and Majestys with that style of mount had the mount offset towards the rear, but those mounts appear different to what is being sold nowadays.