Advice on an old Opticron IF75 (1 Viewer)

I'm thinking of buying an old IF75 as I can get one for very little money. I use an ED50 99% of the time, I was just thinking of getting it for seawatching/looking over lakes. The scope I am looking at comes with a 30x though it appears to be tiny. Can anybody recommend a decent eyepiece for the scope? Would this work for example?
Cheers.

I'll be honest Daniel, I don't think you will be happy with the scope for your planned use. The ED50 is ED glass, the IF75 is bog standard crown glass. The difference in image quality is really going to show.
I used to have an IF75 many years ago but traded up through other scopes until now I'm using an Opticron ES80 - every time I moved to a new scope the image quality was better, there have been 3 scopes between the current one and the IF75 which is why I reckon you will not be happy. I've also got a GS52 ED scope body which is almost as good as the ES 80 in terms of brightness and definition but the lower mag associated with the smaller objective means I can appreciate your idea of getting a bigger scope for seawatching etc.