In my boat, I want -
keel stepped mast
I don't want -
center board/swing keel
In-board diesels are pretty common...but an Atomic 4 in good working order is a pretty good and safe engine... so you might want to at least consider it.
Sloop rig... pretty common... might also want to consider cutter rigs, since they're pretty similar, but give you a bit better options in heavy weather.
Roller furling jibs are pretty common and can be retrofitted to almost any boat if it doesn't already have it.
Fixed Keel—wing, fin, full, bilge, twin??? Want to narrow it down a bit more. Wing, bilge and twin keels give you a bit shallower draft, while losing some performance. A full keel gives the prop and rudder more protection most of the time, since the prop is usually in an apeture, but with reduced maneuverability usually. A fin keel often gives the best performance, but often leaves the rudder and prop more vulnerable.
Keel stepped mast. As previously mentioned, in this size range, you may want to consider deck-stepped masts as well. One serious advantage to a deck-stepped mast is that the interior of the boat stays much drier, since there is no big hole through the center of the cabin top.
Wheel steering—tiller steering is fairly unusual on boats in the 32'+ range.
Cored Hulls—might be worth considering, since a lot of boats have them now. Cored hulls allow a boat to have a lighter, stiffer hull than they would without cored construction. Eliminating cored hulls gets rid of a lot of otherwise very good boats.
As for Mizzen Masts, Center Cockpits, Centerboard/swing keels... these are usually features that are less common, and should be pretty easy to avoid.