Just a couple of thoughts.

Don't go with the metal butt. I have one on a 9.3x74R and you can not sit the rifle on anything without scratching it or worrying about it slipping. I usually put a lace on recoil pad just to protect it.

Balance is more important than barrel length. I am not sure a Holland will balance correctly with 24" tubes in the 375Fl.

I like the lever forend release. It seems much more likely to work all the time. No stickyness. I have had three Royals and all had lever releases.

I love the choice of the 375Fl. A grand cartridge and plenty of poop for what you want. Much more practical than the 40+ calibers and a better all around cartridge than the 9.3. Plus it is a Holland after all.