Walker--have installed at least 9 or 10 in 40 coupes with small blocks, cooling concept fans and AC--no problems.
https://johnsonsradiatorworks.com/ FYI Just saw an add for Johnson Radiator Works today in the NSRA Street Scene Magazine. went to the web site to see what they had on there. The first thing that comes up is notice that they are 8 to 10 weeks out on orders. A 39-40- Rad will run you about $1300.00. As most of us already know Walker went out of business a while back but Johnson has purchased all of the tooling and propriety processes , moved and set everything up in his area. I read that he wanted to continue the quality and workmanship of the Walker radiator works. They just would not let him use the Walker name. Johnson is offering a 5 year warranty and from what i read that includes labor for the change. I suggest checking the web site out to verify that. As I have said before I have a Walker in my 40 coupe and another for my 39 Tub. I am having the radiator for the Tub checked right now to make sure it is sound. It's been sitting around for close to 30 years and had some baby vomit looking stuff dripping out of it lately as I work on fitting it and a fan to my project. I hope my radiator guy can clean it out and pronounce it healthy as I don't want to spend the 13 hindered bucks if I don't have to. https://johnsonsradiatorworks.com/
I have a CAR (custom auto radiator) in my 40 with a mechanical fan and no shroud. I have had no cooling problems , except for the thermostat. I use Robertshaw thermostats now.