You are going to have to buy the entire keyboard to harvest the stems to transplant. Though I hear that the stabilized keys are a bit trickier.
I feel that the closest MX to Topre would be ergo clears of some fashion. Though if you want to try stock clears, those feel nice as well, but nothing MX will be as tactile as Topre.
As a note, I do not own any Topre switches, just from what I have tried at Keycons and meetups. I have tried lubed ergo clears, stock clears, lubed stock clears, and a couple other variants.