Some of the 26” radiators had similar sized cores. There were versions that were taller, but they wouldn’t fit your A body with the hood closed. So, more than likely you will have no issues using a 73+ 26” A-body shroud on your current radiator. That will of course depend on how your radiator was mounted, because clearly your car has been modified. But a later A-body shroud for a 26” A-body radiator is where I would start.
There are advantages and disadvantages of going to electric fans. They can be a better option for a lot of applications, I love the electric fans on my car. My point was that installing electric fans correctly requires more work than most people realize, they’re not something you just slap on and have work properly. You need to asses both the cooling requirements of your car AND the electrical capabilities, and make sure your fans and your car are set up correctly for both.
In your case, I would still figure out why you have an overheating issue first. Even without a shroud a 26” radiator should probably handle a stock 318 if everything is working the way it should. Before I bought anything mechanical or electric I would tune up that engine and investigate why it’s running hot.
