Tannoy Crossover Capacitor 1000V ?

This is a Tannoy supplied schematic, correct? I still find it odd that they'd recommend such high voltages. I believe my HPD's maybe came with 150v.

Are all of those caps in parallel?

Do you have a specific budget? Some brands such as Sonic Cap or Duelund can make custom sizes.

It was supplied by Tannoy, and is from the "System 15 MKII" drivers. I'm quite sure they are in parallel. No specific budget, what ever works well. I have a feeling it will be fine without the high voltages, I spoke to a tech today that has been in it for years, and suggested not to worry about the such high voltages. He said it was probably because Tannoy at the time had tons of those specific caps, and they just used those for cost. If you have any other input, great, and thank you!

I would just use a good 4.7uf on the HF unit, that would really open up your choices. I recently tried a pair of Obbligato Copper Caps and thought they were fantastic. Sonic Caps also aren't bad. Or you could go crazy and check out Claritycap MR's and Duelund.

Is it ok to go .1 uf under ? I'm assuming that's ok since it's so close to a total of 4.8 uf, I'm still learning!

Side note, I was cleaning some pots from a Yamaha Preamp, and I noticed that the top of both of capacitors seemed slightly bowed, or curved like a bubble on top...It sounds fine, but is this a sign they should be replaced? There is no leakage that I can see.

Since it's under a 5% change, you should be ok. As I mentioned above, some manufacturers can make custom values for you though.

As for your Yammy, bulging caps are never a good thing.