A quick look at Kodak tech pub J-78 for D-76 shows the slopes of temp vs development time varying by a factor of 1.7 across 6 films at 1:1 dilution. With that much variation using the same developer and dilution, I don't see how you can generalize usefully using the factors you quote across different developer formulations or different films.

Better to go with the charts as PE and others have said.

Lee