All wise advice...but I would go ahead and wing it with a 1.5- 2uF cap (8 ohms). You'll be OK with a 300B SE amp played at normal levels. Wisdom only gets you so far.
The extra overlap provided by the 2uF first order cap will enhance the leading edge definition of the 755C nicely.
If you use a 1uf or maybe 1.5uF cap on that 8 ohm tweeter, you might find that there is no need for an L pad because the tweeter will be rolling off already where the 755C runs out of action.
I did it before and I'm planning to do it again, when I pick up a pr of 3000s a friend is holding for me. This will be on 756Bs, one of which I got through the kind intervention of Bowtie Tom incidentally!
Every time I do this sort of hookup, I rediscover that the cap type influences the outcome more than the exact cap value. Try a few different approaches and use your ears to decide.
"In theory there is no difference between theory and practice. In practice there is." Yogi Berra
This is ears-on, experiment based system design.
Here's a pic of my 756Bs with 2uf WE caps on top, wired and ready to go, waiting for my tweets!!
If the sound blows my mind, I will permanently install the 3000s in the cabinets.
I am not worried about my tweeters at all with 300B and soon-to-be finished 275A single amps.