I do not know. I use the stock mcpcb.
Maybe the Kaidomain mcpcb will fit… the 20mm looks like it has very similar cutouts to the one Sofirn uses. I do not know if the kaidomain is thicker.
Here is a photo of the SC21 Pro mcpcb, next to the Kaidomain 16mm and 20mm,
I have not measured the SC21 mcpcb, but the lens in this photo is 20mm:
maybe try a 20mm, and maybe also get a 16mm?
or learn to reflow onto the stock mcpcb?