One on a part follow up
I'm working on a large brass ensemble transcription (gasp) of highlights from a Puccini opera. I always immensely enjoyed playing Puccini's operas even though the low brass parts are sparse (understatement). The music is beautiful for so many reasons, but I particularly admire his orchestration.
Puccini's orchestrations are often an embarrassment of riches - he wrote for a large orchestra, was not afraid of orchestral keyboard (piano, celeste, organ), and often employed exotic percussion instruments. If you compare a page of his orchestral scoring to the piano/vocal score, you might be surprised at just how simple the fundamental ideas are.
This rich orchestration makes transcribing his music a challenge and requires some important choices. As you may remember, my basic approach to arranging for brass is a one on a part concept; doubling up only to thicken or color a line. Puccini colors and thickens - a lot.
The choice then is whether to try and emulate some of the color and balance choices (always remembering that the sound in his ear/head was that of a late 19th century pit orchestra), or to work from scratch, being economical with first choices and then trying to add color and affect balance as you will.
I believe it's a trap to try and make a brass transcription of Tosca sound like Puccini's orchestra - my choice is to preserve the basic musical ideas and add my own color.