My apologies, feelinfroggy777, i misread your post. I though it started with 'No, CPU will hit 144hz constantly' - as in, the CPU will defo hit 144hz I should have put my glasses on!!!
Having re-read your post, yes, I agree, too many variables for accurate answer. Including all those things I mentioned. So I completely agree, and will learn to get my old man glasses on before posting!
The 2600 will work just fine with the 2070...the 3600 will drive the 2070 a bit harder but I doubt you'll ever notice the difference between 100 or 115 fps anywhere but a benchmark...in actual gaming the differences would be so small as to be unnoticeable, especiallly on a gsync or freesync monitor.