There used to be radiator shop that rebuilt the brass radiators not nessesarily cheap anymore maybe it was referred to as rodding or re-rodding,where the tubes in the radiator were desoldered ( by gas flames ect) and replaced with new tubes of the appropriate length.....Just for informational recollection, I know you could solder off about 12 of the tubes (when leaking)WITHOUT AFFecting..cooling capacity range. Meaning if a bolt hit 3 tubes or a given number up to say 12 tubes and cut them", thus spewing water /antifreez like heck", you would pull out your needlenose pliers", and your ruby soldering flux ( kestor acid core?) Suggested oatey 50/50... heat the tube were it joins the brass end header ( collector comb) and twist the tube with the needle nose untill it came out of its socket then tin the end and fill hole in with the oatey/ Kester solder on each end of the damaged tubes ,( doing so quickly as not to deteiriorate the surrounding joints ?) Then not forgoing to pressure test the joints (low air pressure )before useing....while a single ding gravel chip to say 1 tube could usually be fixed with draining coolant ,and drying the hole with solvent like gumout/ acetone befor applying jb weld (12 hour version) and allowing to cure.. Oh yeah: I have one of the old brass jobbies laying in shed outside it might even be 4 core ( row) ect...If I had my choices about soldering' it would include a brass/ copper design instead of steel or aluminum ...