New caps from Digi-Key have arrived and they were very well packed.
I went with them because they have a decent selection of 500v caps. I wanted them to replace the six original 475v rated caps.
All the caps are rated for 105C and long life. The two caps in the B+ voltage doubler are also rated for high ripple current.
The main B+ runs at 330 with a voltage divider tapped for 235 and 120 - all well below 475.
Then it occurred to me it uses a solid state rectifier so B+ will be available instantly while the tubes are still warming up.
I expect B+ runs fairly high until the tubes start conducting.
Two of the caps are 4uF and the only 500V+ ones at Digi-key below 10uF are surface mount.
10uF would probably work just fine but I decided to give these 3.9uF SMDs a shot. I think it'll be easy to solder on extension wires.