I always was told run the longest shock possible in drag race application. If this is a s s spring car it's about the extension on launch. I thought not sure they could be in the range of 29"L . Looks like what you have should work. after installed measure it for the the amonut of extension. Run it see how it works. lots of variables HP, Converter ,etc.
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.)