Re: 59 n in the bridge?
Of course it depends upon your specific guitar, woods and all. The '59 is a very good and versatile pup and can be used effectively in many guitars. Likewise the neck pup can work very well in neck or bridge, again, depending on your guitar and depending on what you want to achieve, tonewise.
If you compare the '59n in the neck position with the bridge position, it will sound a little weaker and thinner in the bridge (less output, less mids). But if that's the tone you're after then you'll love it.
I first had my '59n (with a UOA5) in the neck of my Wilshire. It was a bit spikey (piercing highs) for my taste for a neck sound so I put it in the bridge where I think it works much better. I think, however, that the '59b (with UOA5) would be better than the '59n, but I'm happy with it. It's a very fine pup.
So to answer your question....
No, it won't sound drastically different than a '59b, but it will sound slightly different. Put the '59n in your guitar in the bridge position and see what you think. If it sounds good, but you wish it had just a tiny bit more output and a bit less treble spike and maybe a bit more mids, try it with an A8 or UOA5. If that does the trick then you are happy. If it's not quite there but you still like the sound and performance of the '59, then try a '59b.
The '59 (n or b) is such a great pup, it won't be a waste to try it out.