90 was the factory for over 10*F, so 75W-90 would probably be the best modern equivalent.
Might see what Dr Diff or some others have to say but the 140 seems really high viscosity in comparison.
As a tribute car it has to do street and strip, and I assume your not tearing down after every event or two. That's one aspect about engine racing oils people seem to ignore when they use them on the street.
