MP rear shock ext length ?

FWIW...I previously spoke to John Calvert on this when I had to get new rear shocks last year. His rule of thumb was 4" of length beyond static installed length. My static was 17.5" so I went with a shock that has an extended length of 23-3/4" and compressed of 15". (My car has CalTracs with the split mono springs and good body lift on launch.)