Winch sizes

lewmar or harken 16st is the proper size for the sheet winches.  They are the smallest self tailers both of those companies make.  Anderson makes a beautiful 14st that I am sure would be sufficent for the sheet winches.  Lewmar also makes a 14st that is not as tall as the 16 that would work for the cabin top winches.  For new winches your lookin at about 1200 big ones per set.  I almost replaced my sheet winches last year when i found a set of used harken 16st's for sale for 650 bucks but instead I replaced my broken roler furlling.  Another thing you could look at for your cabin top winches are those little plastic discs that go on top of non selftailers that turn them into selftailers.  I have seen them on other boats before but never used them myself but i understand they work well if you cleat the line after winching because they can slip sometimes.

I too have a pair of Lewmar 16CST self-tailing sheet winches set on the cockpit combing like Andrew's.  Although I really like them, they are single-speed units.  I am seriously considering installing a couple of regular Lewmar 16's (non-self tailers) so I can have the extra power of a two-speed winch on each side of the cockpit as well.  I also have a couple of Lewmar 14CST self-tailers that I have earmarked as replacement winches for my two old Barlow cabin toppers...like Mark suggests.

I replaced my winches with Anderson 28 selftailing two speeds. They were expensive ($1930CAD) and definitely overkill, but are great for single handed sailing. You just have to be careful and not crank until you rip the sail right off the rigging.