I have a Browning Safari Grade in 30/06 with the FN Mauser action. Is this action big enough for a 375 H&H?

with a good smith, yes...

it would be a better case to sell the browning, get a cz 550 and restock as required.

besides, the cz will hold more than a quarter box of shells
jeffe

The latest Guntest Magazine trashed the CZ. They were testing one in .416 Rigby and had serious probles with the safety and feeding of the last round. IIRC, they opined the one they had in .375 H&H would probably have at least the same safety problem. They called it a, "Do not buy." I can't say if it's a quality control problem or just a case of a bad one slipping through.
Paul B.

Paul,
(just kidding here) and if they reviewed a remington and the bolt fell off, would they slam big green or just not run the article?

heh
jeffe

For what it's worth, Gun Tests magazine shot a whole quiver of arrows at Winchester's M-70 .375 African a couple years ago as well. Serious flaws such as not feeding and ejecting properly. They really lamblasted the Winchester folks.could remember why I didn't renew my subscription.......but I didn't.

As Jeffe said, a good gunsmith can open it up without much problem. Unlike Jeffe said, I definately would not trade down to the CZ, just have it opened up when you rebarrel, maybe a little feed work and you're in the big bore game. The commercial FN large ring actions are some of the best available in my completely unbiased opinion.