length difference in 70 6cyl swb driveline to sbc line?

[Enygma]

got a project a 70 steppy came with 305 and TH350 out of a 83 firebird- dont ask
was originally a 6cyl 3spd -longer motor hence my drive shaft is too short (about 56" center to center of jonts- 'about')

a stock 1 piece driveline from sbc motor ahould work right? i dont want to lengthen too much $ and there are lots of boneyards around, i can use u jonts i have..

how long is stock driveline for shortbed v8?

thanks guys!
and yes i searched- so much info here my head hurts