Recapping 1964 Gibson Falcon

[puffybear]

Hi folks, I'm new to posting. I have acquired a 1964 Gibson Falcon, GA19RVT and am in the process of updating the caps. I have already changed the 2 prong cord and have replaced all the multi-section and other filter capacitors. I was going to replace the bypass capacitors, which are the old sprague molded plastic over paper ones that are wired onto the terminal board. They are 20uf @6volt and I wanted to replace them with some modern ones of the same value but my search has been fruitless. I can't find this value of capacitor anywhere. Does anyone have any experience recapping this old amp, and can they give me some tips as to where I might find these--or--whether a 25uf@25volt capacitor will do,or will it screw it up?

Thanks so much