A few years ago I re-ground a screen for my Microcord TLR, it was then much brighter than the original. Later I fitted a Chinese screen which was slightly brighter and has a centre focus spot, it's excellent. I'd bought it for my Yashicamat 124 but the screen sat in a drawer in the UK, and the camera is only used when I'm in Turkey.
My experience is that most older screens are quite dim Graflex screens even on the Super Graphics and MPPs all benefit on having their screens replaced or reground it's an improvement of a bout 2 stops apparent brightness, that was certainly the case with my Microcord. Some companies screens were much brighter by the mid 1950's but not all.
I probably have glass already cut for a Microcord/Rolleicord screen so could help you out if needs be, I'm only 20 mins from Birmingham.
Ian