I have had the radiator out of my 75 three times. The first time was for a new radiator. The second two times were for cam swaps. This is what I found to be easiest. However, the differences in years may make a difference. So, for what it's worth:
Inside the front fender wells are the bolts that hold the radiator support. Remove the top two bolts on each side of the car and loosen the bottom bolts. Of course, you would first remove the brackets holding the radiator to the radiator support. By removing the upper bolts in the radiator support, you can swivel the top of the support towards the front of the car. This provides room for the radiator to slide out of the the space between the support and the shroud, without having to remove the shroud. After the radiator is out, you can easily remove the shroud if you desire.
Installation is in the reverse order. It is advisable to have two people lift the radiator out, one on either side of the car. Oh, by the way, I should mention that you should have the hood off of the car in order to perform this operation. Scribe a mark around each of the hood hinges before removing, so that you will not have to mess around with realigning the hood upon installation. Again, this procedure may be somewhat different for your 78.
I mentioned earlier that two of the times that I have removed the radiator were for cam changes. Well, I must say that it took longer to R&R the radiator than it did the cam!! Don't get frustrated. Just remember how one eats an elephant . . . one bite at a time.
Ron