Buy an English made 375 (Holland etc) or have a look at them
as they tend to be made lighter and svelt.

See a Holland at
http://www.westleyrichards.com/gun/used_guns_2_product.php?id=25453

I have had a couple and they are easy to carry.

You could then get a gun, have it rebarreled and the
stock reshaped to lighten them up.

500 Nitro