I had loads ltd cut me a 28 in wide 13 in tall radiator for side to side tanks. Excellent quality, no complaints. I then used my trusted oldschool metalman to make me the end tanks, braces and feet with rubber cushions. Soldered it with good quality flux and new solder wire from bought from Bohrapir.
Never had a problem. Radiator making is not just slapping parts together, the tanks must be tight fit and the solder used to seal only, not for mechanical strength. Proper installation is also mandatory as vibration kills radiators.