If it has a 2" back you can use an eyepiece that has no field stop, or almost none, to give you the widest true field. Those Hyperions are only 1.25" barrels, limited to what you're getting with your old 40mm. Try these:
TV Nagler type 5 31mm,
TV Plossl 55mm,
TV Panoptic 41mm, or 35mm,
Paragon 40mm ( no field stop),
Vixen LVW 42mm, similar to panoptic;
Vixen LV50mm, better than plossl but smaller apparent field than the others above.
Take look at
http://www.televue.com/engine/TV3b_page.asp?id=214, what matters is the column labelled 'field stop'