I checked out the HMS Suprise on the net. Holy Christ!!! I tip my hat to you sir. 1:48 scale. At $700.00. Over 4'-0" in length.

Get it!
Regarding brass.
I think brass will tarnish with time. I have a couple of brass server trays my mom had cleaned some years ago and they are showing a pretty good coat of tarnishing. If not find a piece brass somewhere and test different solutions. Then with a fine brush you could weather the brass on your own. If not asked someone who deals with brass. Such as a musician, plumber, etc. They may give you a tip on what works with brass. I'll check with a couple of architects, engineers and/or contractors and see what they say.