Looking back over this thread it appears you added holes to the top of the fan shroud. Curious why ? I built a very similar style shroud for my roadster, SBC powered and it is still running too warm for my liking, in traffic temp still climbs up into the very uncomfortable zone. Mine is solid across the top, as in your original design. Was it done to solve a running warm problem ? As I've noted before.......awesome car !
The reason was, when I first built it, at around 70mph the rad would shake. I couldn't see anything else that could cause it and the wheels balanced fine, so I took a shot to see if there was turbulence from air being trapped at high speed. Turned out not to help and mostly just a bias ply, old steel wheel problem I believe.