Need help on transmission choice...

[69chevy lwb]

well the nv3500 will come out in the factory location of a 4 on the floor so you will need a high hump if your not opposed to a hydraulic clutch it would be a good swap the nv3500 might require you to have the drive shaft lenght changed which is not a big deal im not sure what you mean by crossmember though my truck is mounted at the bell housing rather than a transmission mount so the trans just hangs there i dont really know anything about the t5 swap