The Nikkor W 240mm has got a 336mm image circle so it will cover easely the 8x10 format. I never used it personally but it should be a fine performer. I have the Nikkor -w 300mm and it is as good as it gets, course there are some more evolved plasmats like the apo-w with some more mm extra coverage but 420mm is more than enough...
I also got a SS Hm 210mm and its a nice (very nice) performer but it does not relate very well to the Symmar-s 240mm.

In 8x10 you cannot find many bad lenses, especially after coating.

Another thing, quality improvement in these tipe of photography comes more from good printing and good technique.
Both lenses you mention should give you stellar images, if you are a good photographer...