After reading these posts I got the brass 4 core from classics industries. No problems with thickness or the attaching the shroud.

Results: On a 95 degree day in 45 minutes of stop and go traffic it lowered my temp from the usual 211 to 191.

CAVEAT: It is about a half of an inch wider and crowded the battery tray. But it did use the factory radiator support walls holes.

Also got Classic Industries spiffo temp gauge radiator cap, which proved to be completely bogus and inaccurate. Suspended in boiling water it read 225 degrees at sea level