Someone I know lost their DW to cancer last year, after quite a long illness. 3 years ago they got a kitten, and as DW worked near home this was not a problem.
Friend has a job which involves a fair bit of foreign travel during the week, cat is a fine strapping neutered tom, with a love of hunting. Ideally friend would rehome the cat locally. But how? Is Rescue the only way?
Luckily, it sounds as if there's not real time pressures on this one?
I'd suggest that he casts a wide net - with your help, if available. Does he mind seeing the cat around locally?
Name with local rescues, spread the word among friends, neighbours, work colleagues and any local vets, any clubs/pubs/ associations which he or you attend, and possibly an advert on the catchat forum.
Might be a good idea to make up a flyer with a picture of the cat and a little history about him - for copying and circulation. If he's a possible mouser (you mentioned he was a hunter) I'd include that as well. Many people are after one.
Other posters will probably have more suggestions.