I have always preferred bolt action rifle for work on DG, a Brno ZKK602 in 500 Jeff loaded with 570gr bullets. It has always resolved any issues with the greatest of satisfaction.
The only exception being follow up on wounded leopard for that I prefer either my 12ga sxs "Poor mans double" loaded with Brenneke slugs or 12ga/9.3x74R combination, Brenneke in the 12ga barrel and a decent expanding bullet in the rifle barrel.
The speed of a leopard attack is mind boggling fast and there is no time to reload a magazine rifle if the first shot does not go true.
IvW
Your choices are excellent and reflect the experienced White Hunter of today . It is interesting to see that you and Hoss Delgado both own a Zkk 602 rifle . They must be excellent rifles . I will have the privilege to try a Zkk 602 in two months time when l visit the United States of America . Hoss has arranged for me to shoot a .460 Weatherby magnum built on a Zkk 602 rifle mechanism . It is the one calibre which existed during my time , which l had never seen any client ever bring to India ( although , l always hoped that some one would bring it , so that l could try it and see for myself how it is .) . Right before the liberation war of 1971 , l finally exchanged correspondence with a client who was going to bring one for hunting Gaur. However , it was never to be .
It was reportedly the greatest invention of the American gun maker , Roy Weatherby and the most powerful commercially loaded cartridge of my time .
I am of same view as you . For Shikar in India , if availability was not an issue , l would use a .375 Holland and Holland magnum calibre bolt operation rifle built on a French Brevex mechanism , loaded with Winchester silver tip cartridges for Royal Bengal tigers and 300 grain metal envelope Winchester bullets for Gaur buffaloes ( although the first shot would need to be with a soft nose bullet , as it would be desirable to fire this shot from the side , so that two lungs are pierced and the bullet opens up inside the lungs ) .
Today , modern cartridges with a controlled rate of expansion have made the humble Winchester silver tip cartridge of my era obsolete . And based on my lay man's understanding of ballistics , one no longer needs to load soft nose bullets and metal envelope bullets into the same magazine for Gaur / buffaloes anymore , due to the modern bullets being able to accomplish everything.
For pursuing wounded leopard into thick vegetation, l would opt for a double barrel rifle calibrated for the .375 Holland and Holland magnum calibre Winchester silver tip 300 grain cartridge. Such a rifle would have two triggers , 26 inch long muzzles ( or less , depending on height and weight of the hunter ) and no automatic safety mechanism.
Alternatively , a 12 bore Paradox ball-and-shot-gun from Holland and Holland , loaded with a 740 or 750 grain lead bullet would do very nicely . I would probably opt for this over the double barrel .375 , because in India at the time , there was a law that every Shikari ( be it client or local ) could only go into the Shikar field with no more than two fire arms .
Since the Brevex would be my rifle , the second gun would have to be capable of firing shot anyway.
On a related subject , is your combined rifle-and-shot-gun an over under or a side by side ?