In GNSSs (Global Navigation Satellite Systems), it is common to use codes with lengths in multiples of 1023 to maintain backward compatibility with the preexisting GNSSs. In general, there is no well-defined family of codes whose length is in multiples of 1023, and thus, codes are usually designed with concatenation or truncation in well-known code families. However, there is no golden rule to choose a mother code family for code design. In this paper, we propose a mother Gold code family selection scheme suitable for code design with concatenation or truncation. In the proposed scheme, a preferable mother Gold code is chosen by investigating the cumulative distributions of the autocorrelation sidelobes of randomly generated codes with concatenation and truncation of codes in the candidate mother Gold codes. With the proposed scheme, it is possible to choose an optimal mother Gold code family with less complexity in a short time.