| I don't know about the ST4s but the ST4 uses the same master cylinders and levers as my carb 900SS. Span adjustable levers are available from various sources for about £30 - £50 the pair. (I got mine from Spareshack) You don't need to adjust the steering lock. All you do is undo the nut on the bottom of the pivot, slip the pivot out, remove the lever and fit the new one, replace the pivot (preferably with a smear of fresh grease) and re-fit the nut. That's it. Even a monkey could do it in 10 minutes.
Only thig to watch for is that the adjuster screw for the cylinder engagement is not too far in. If you adjust them so they protrude the same as the old ones you should be fine. | 
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