I think the dial is original and the radium-based illuminator on the hour mark has a orange-brown patina.
I wonder if the movement (1966), dial and case fit together?
The dial, were it an original, does not go with the movement nor the case. There was not a big triangle (BT) 165.024-64, the BT came in later non date coded 165.024 (no -number after that). If you read through the link I sent you a few messages up, it will help a little.
I think the movement is ok. The dial is not. The bezel is a replacement for sure, and as you say the crown is wrong. There is even something about the case that seems off to me...
The serial of the movement does fall into the 165.024-64 range.
I also think that you should strongly consider the advice given to you so far and look elsewhere. More examples will come up (I'm looking at them too, been searching on and off for a couple of years). The -64 is a particular favorite.
It's really good that you're asking questions here. There are lots of "gotchas" or potential trouble areas when it comes to finding a vintage watch, especially one with significant value to it like these Seamaster 300s. Look at more examples, read the guide, ask more questions, you will become more confident, trust me!
😉 Sometimes it's hard to move past the watch that's right in your hands, but if you have doubts now, those doubts will grow into big regrets when you own the watch.