After testing a few 240-250 lenses the sharpest I had was a Doctor Germinar 240. (Thanks Kerry) Coverage at 8x10 is limited but it beats my Schneider Symmar. Because it's so sharp I use it for 4x5. It is really overkill at 8x10.
About what Ole says, that is not much enlargement. I have a 10" Brass barrel Rapid from before 1904. This baby tested out near the Symmar. 4x enlargement, no problem. I would use it for 8x10 anyday. It even beat out a 300 Fuji tele and a 270 Tele Arton. You never know until you test.