1965 A body 4 speed ball and trunion to Slip yoke ?

Not having one is certainly reason enough. What I was getting at is if he has a ball and trunnion and it is good or in serviceable condition, that's his easiest and most economical way. I do agree what you pictured is a nice option.
The driveshaft i have is from a 6cyl automatic. Do you think the drive shaft will withold the power I am going to put on it ?