There is only one gear set for the F23 that 'directly' bolts up. It has a 3.94 final drive ratio and came only in the 2000-2002 Cavalier/Sunfire with the 2200 pushrod engine. There is no best place to get one, but you can start here
That site will find interchange parts for you so just enter 2000 Cheverolet Cavalier and select the 2.2L engine and manual transmission. If you put 2002 in there, it will also give you the option of the Ecotec 2.2 (VIN F), which you don't
want as the bell housing won't work.
If you want to go nuts, you can look for a 2010 Chevy Cobalt with the XFe package (Opt FY1), it's F23 has a 3.63 final drive, but you have to swap the bell housing half of the case. Doing this makes mounting the trans even more interesting than it already is and if you don't verify that the trans is shimmed properly inside, it may not live very long.
Cavalier/Sunfire Getrag F23:
Fiero/FWD Getrag HM282:
[This message has been edited by carbon (edited 05-15-2014).]