The best 65 last fit for me is 7EEE, with that the heel is a tad bit wide, and the instep is snug (on bals). Heel to ball feels perfect, and width across the ball is good as is room in the toes. I also have some 65 last bals in 7.5EE (your size), and they fit pretty well, except there's a bit more pressure on my instep than I like, and on some I get a bit of bowing due to the width of my mid-foot. The heel size is perfect for me on those though.
7EE in the 511 last is good heel to ball, good in heel width, but a bit short in the small toes area (not uncomfortable, but I'm aware that my small toes are touching the shoe and I wouldn't be comfortable if I wore anything thicker than thin socks). There's plenty of room in the instep. 7EEE remedies the toe room concern, but is too wide, especially in the heel (even with medium weight socks). 7.5EE has just too much volume all around, although heel to ball still felt good.
Did you get Dundees in 8E like your Daltons and they were too big for you?