That is correct.
The most popular conversion cues are the Brunswick Titlist cues.
Brunswick BBC (Brunswick Balke Collander) and the Brunswick Tru Balance.
Those are the ones I am familiar with. As Doc said, maybe some 2 piece.
Willie Hoppe cues come to mind. Probably more than that model.
With the older 2 piece Brunswicks or others, I would say a bit of a spiff up job. New shafts, joint collars, refinish, wrap etc. Not a conversion in the sense that you are using a one piece house cue, but a conversion in the sense that you are taking an older cue and giving it (converting) and giving it a new beginning.
Another popular conversion one piece is the Dufferin when it was made in Canada.
I have some fairly nice Valleys in the dungeon as well. They won't make fancy schmancy players but they will be nice trunk cues.