Like I said before you can mount the motor with the existing mounts but will sit back towards the firewall,you can use the bellhousing flywheel and clutch parts from the six plus your existing trans. If the block does not have the hole for the ball for the Z bar you will have to drill and tap it or find a older motor that has it,the Z bar will need to be shortened on the motor side some to use with the V8. If you use the six mounts and bellhousing there will be no need to move the crossmember unless you want to use a automatic trans and then that crossmember will meed to be removed,back in 83 I installed a 1970 350 in a 1967 C20 that originaly had a 250 and retained the original 4 speed like I mentioned above.