>>1420500the levers you have are four finger, best suited to medium profile cantilevers (as seen in the 1980s)
it is not recommended to use this type with v brakes as the pads do not move far enough and grip too violently when they do make contact
also they only work if your rims are super strait (less than .5 mm +-
and the distance between the end of the noodle holder and brake cable anchor bolt must be 45 mm
the cable its self will only move 5 mm
and the pads less than 2 mm
Shimano ST AT20 and ST m290
are three finger levers for low profile canter levers (later into the 1990s)
they work ok for v brakes and the thumb shifter from Shimano SL-m453 can be attached to them (SB-CT90 also can do this)
but this is not really the best solution
to reuse the shifters either you can get some shift lever mounts that are separate from the levers
like SL-MT60 (SL-MT62) and SL-M730 (SL-M732)
or something akin to
http://www.bikerecyclery.com/precision-billet-thumb-shifter-mounts-turquoise-blue-shimano-rare/http://www.bikerecyclery.com/precision-billet-thumb-shifter-pod-mounts-3dv-purple-ano-rare-exc/there are four pins in the shifter its self
and up to 12 holes in the part that the shifter mounts to so it can be placed at three different angles
I do not know what the system is called but SL-CT50 and SL a250 along with all the early rapid fire shifters use it
but it was discontinued by the time v brakes came into use (1997 to 2000 ?) typified by ST-EF20
here is a site that lists some of the parts
http://www.fa-technik.adfc.de/Hersteller/ 