I had the old metal levers on a Troubadour III replaced with Loveland levers and they work well. The trick is you really should have a harp technician do it because it will mean drilling new holes in the neck and each lever will need to be regulated. There’s the cost per lever (depending on the type you want) and the cost for the labor.
If the neck is not warped, it should work well. If the neck is very warped, it’s probably not worth it because it will be difficult, if not impossible, to get a good regulation. On the old (I through V) Troubadours, the neck and column are one piece; replacing it would mean replacing half the harp; not cost effective. The new Troubadour VIs have a neck separate from the column.