They're sold already.
Things to know about conversion parts and they're use for converting back:
1. Hammer heights vary slightly but here are the four basic size ranges. OM hammer heights measured from bottom surface to top front:
Large frame hammer = 2.370" - 2.380"
Mid-frame = 2.180" - 2.220"
Single six, tall for fixed sight = 2.035" to 2.060"
Super single six, shorter for adj. sight = 1.945" to 1.965"
2. 3 sizes of cyl pin lengths for 3 frame sizes, but the conversion pin can be used with the old parts.
3. cyl hands, two sizes, small frame and mid/large frame. The conversion hand can be used with old parts, it's the same part.
4. The cyl bolt (latch) is the same for all frame sizes; this part must be replaced with an old model.
5. The conversion trigger can be used with old parts, it just needs the transfer bar mounting lever hack sawed off the trigger. All triggers interchange between all three frame sizes. The wider Super BH trigger needs a wide trigger slot in the trigger guard.
PC Bisley hammer for old models:
http://powercustom.com/store/index.php?main_page=index&cPath=12&sort=20a&page=3
If you choose to use the PC Bisley hammer:
MODIFYING BISLEY HAMMER/TRIGGER FOR PLOW HANDLE OR BIRDSHEAD GRIP FRAME:
It's just a matter of dressing down the hump to fit the plow handle grip frame backstrap (as is done with the large frame Bisley hammers on center fire Rugers.)
Before you trace your old hammer, make sure it fits flush with the grip frame 'ears'. If not you'll want to leave the Bisley hammer larger than the original to final fit flush with grip frame ears.
Use the hammer pivot pin to hold the original and new hammers together and scribe both sides, then grind, file, sand and re-blue (if blued), the portion you filed away. If hammer won't cock, the issue is that the back of the grip frame slot just needs a very slight lengthening with a small flat or triangular file.
I "hog off" most of the metal with an 1/8" x 1" Dremel course stone; hammer in a vise, or use a cutoff wheel mounted in a bench top grinder. Then true up the course grinding by 'draw filing' with a small double cut triangular file and then square up the corner at the top of the hump. Finish with 600 grit paper wrapped around a 1/4" x 1/2" alum sanding block with flat surfaces, heat with hair dryer, and re-blue with NU Blue or Brownells OxPho blue. That will match the factory finish which is not a high polish. For a higher polish, follow up with 800 grit and 1000 grit. Polish with a Dremel flannel wheel using white rouge made for polishing stainless steel. Then blue.
http://www.rugerforum.com/phpBB/viewtopic.php?t=136817
http://www.rugerforum.com/phpBB/viewtopic.php?p=1543606#1543606
Stock Bisley hammer in rear, modified Bisley center and standard hammer in front:
(photo by G2)