C6 tranny to T5 - Driveshaft length

Hallo, I'm from Switzerland and own an 1969 Mach I. My motor is an 351 Cleveland with an C6 transmission. Now I want to built a T5 manual transmission, and I don't know if I've to change my driveshaft ?? Is it to long or to short ?

Thanks for the answer !

For a cleveland and having the ability for quite a bit of power, why not go with a t56 or a tko tranny over the t5? To answer you questions, attach the tranny, then measure the distance between the two.