Mike, Bob; .40-65 WCF and .40-60 WCF are not interchangeable. .40-65 was originally an 1886 cartridge, longer and more heavily loaded than the .40-60 1876.
(Confusingly, .40-60 Marlin is the same case as the .40-65 WCF.)
win94oz, I think you will have to rebarrel a .45-70 to get a modern .40-65 repeater.
There are a lot of .40-65 single shots out there - I have one - but they are meant to substitute for the .40-70 Sharps with common brass. I am at present loading a 420 grain bullet for my Browning, whereas the original repeater load had a 260 grain bullet.
Have you thought about a .45-70-300?
A friend here loads his .45-90 and .450 BPE with the 330 gr Gould Express bullet, which does very well.