65 Barracuda Fromula S - what to do

First I would say, if the 273 needs to come out and gone through then you might be better off replaceing it with the 318 for now saving you some coin there! Second, I would definately swap the rear end out for the 8 3/4-one you already have it and two if you would want to swap gears that rear gives you that option for very little money and work-except a replacement pig! Third,as you said if you change the rearend then you have to get a new driveshaft, not a bad idea anyways since you might as well have it balanced and it will have new U-Joints so that will be an upgrade. As said in earlier posts none of these changes will permanently alter the originality so as not to put it back to stock. Just my opinions here but those are what I would do if it were mine. Greg