Hi From what I have seen on a number of rads that have had spot repairs done that are this old, it"s probably time to go for a re build on this one if the top and bottom tanks/sides and mountings are salvageable. or find a good quality new one if it exists. I seem to remember the tubes are soldered inside the tank and it runs to the outside a bit so this is kind of a cheap fix i think by the looks of it
A guy has to remember this thing has been expanding and contracting in use for probably over 50 years. The solder joints get weak and you will just keep chasing the leaks round the top seams and cooling tubes. Chances are Probably you will get it good and in a month it will leak 2 tubes over or split 3" up the header seam when it finds the next weak spot. Rad repair is not cheap any more and you would be happier with the first bill and it"s right, when you count the lost time taking it off /running to town to take it and bring it back later, and the cost of antifreeze you lost on top. This is my experience from a good few years working on old tractors in my shop for my self and customers . You have to make the choice in the end thats right for you, it's your money, or the governments if you don't spend it first lol . I know what mine would be right now.
Good luck with it.