I have this Escort Sport 'box with a Quaife straight cut cluster, lovely ratios, the zetec it's mated too producing about 175BHP.
Whether to go for a 5-speed of not depends on a few things, what diff ratio you have, what sort of power the engine makes. Then the standard type 9 ratios may not be suitable, and if you go for a straight cut type 9 then you also (probably) have a straight-cut 5th, giving plenty of whine at cruising speeds. 4 speed 'boxes don't suffer from this as top is direct.