Christy makes a good point, which reminds me…..if anyone is seriously considering replacing Lovelands they might consider Rees levers, available from both Robinsons and Musicmakers. Rees need only one screw, like Lovelands, so you could probably not need to drill any more holes; except possibly for a stop (aka “retainer”) for the largest strings. They also cost less than either Truitts or Camacs.
Not to be argumentative (well, OK, yes but in the interests of clarity): If the old holes are filled with glued hard wood dowels there will not be a degradation in the neck’s strength – in fact it might be slightly stronger. A skilled crafts person would also be able to hide that repair.
On the subject of “do it yourself” – levers that engage the string from the back of the string such as Truitts and Rees’ are easy to mount – string tension holds them in place while you mark, drill and screw in place. Those like Lovelands are harder to keep in place if you have little experience, since string tension pushes them away from the neck when engaged.
I suppose it is more feasible for most harp makers to stick with one or two types. However, if there is enough wood below the bridge pins there is no reason not to order a harp that you otherwise like unlevered and mount the lever type that you prefer. Or have someone do that for you – it really is not difficult.