Same cams between 350f and 400f. The 466 kit will not fit in the 350f cylinders, but you could swap out the 400f cylinders, head and studs if you wanted. I don't think it is worth the effort (better to just swap in an entire 400f engine), but that's just my opinion. the 400f head does not line up all that well on the 350f setup and will require some minor modifications.
The 400F stock pistons are a good swap into a 350f cylinder. They take the 350f liners to their very limits just like the 466 kit does to the 400f engine, but they are a huge improvement to the 350f... supposedly.
I've ported out a 350f head and it made a world of difference. I have one coming from Rieck that was ported and rebuilt, which I imagine will provide even greater benefits. The 350F ports weren't great, and should be cleaned up if you radically increase the engine displacement. The next choke point is the carbs, which I'd recommend to bore out (DenoonSp is a good option for that) or replace. Boring out the carbs and increasing the displacement will not overly tax the intake and exhaust systems, and should not require extensive rejetting work.
Camelman