The hunt for a PAM 213 rep will never cease, yet sadly there has never been one ever made. However, for the same case with slightly difference on the dial, why don't you go for the sister PAM 212 Flyback? Our reputable dealers here offer the 212 and 253 flybacks, both 1950 case. Asian 7750 and Swiss are available.
Just curious on your last note, why a white 213? In the PAM world, a white chrono/rattrapante on a 1950 case does not exist. Isn't it an immediate spot on?
The movement that PAM213 uses is not easily available and even if it do, the cost will be rather high for the rep factory to produce it. The rep factory will usually go for standard ETA swiss or asia movement which are widely used on gen for all the major brands.