I have Hunter 49, cruising ground is Asia and Pacific, been doing it 14 odd years. You want a Manson Supreme 80lb 36kg anchor. When I bought the first one, it was the only one certified by Lloyds. This may not be the case to day. I'm using 10mm chain and have personally had a chain the (8mm chain supplied) break and also put a few different chains through a break test. There are many schools of thought regarding anchoring, Anchors, chains etc. For ANY hunter 49 or 50 they tend to sail a lot on anchor this results in the links wearing approximately halfway down what ever length of chain you typical put out. So for me on average wear is around the 15 to 20m mark. Due to this action and given Im a liveaboard doing around 10,000nm ever year my chains last 4-5 years, very short life compared to many others. So cruising ground, use, boat at anchor, and the type of ground your anchoring in make a big different to the life time and ware. The comment above about a not replacing but setting up a new anchor and make your old one a second anchor is very wise, and it suggest the same and did this myself. Most cruisers including me initially, if they had a second anchor it was somewhere safe in some whole in case they want it one day, wrong!!!, when you want it you want now. My suggestion is move your existing anchor, including a shackle ready to go to the second bow roller and add your Manson Supreme to your primary setup. Check the chain every 3-6 months pending use at the half your normal anchor depth, part every link for 3 -4m at that point and look carefully in the corners where each link touches the next. I have run on 8mm chain, everyone said I was made, but thats what it came with new. When I broke the 8mm chain, having been in about 67 knots it was then i realized it was not because it was 8mm it was due to the wear described above. It was not due to the chain being to small or undersized as everyone said, it was because I never inspected at this point and it was badly worn due to the sailing at anchor action. As a result only due to the wear I moved to 10mm chain so there is effectively more meat to ware.
Snubber size is also important, you want want the snubber to stretch not snap or be so thick it has next to no give, so I run two different sizes, one for normal conditions, ie <40knots and a larger longer one, for >40knots. I have also run ratio drag tests, and reset tests for when anchoring in tight highly populated spots or where anchoring short is needed.
You might also like to ponder The different grades and types of chains when that time comes, especially if they dont last long as in my case. After not being able to get a clear satisfactory (to me) answer on stainless chain and all the various theories, I elected to run a test. So I am at year 8 now having added an 8mm stainless shackle between 4 links. When the shackle breaks ( or if it does) the four chain links will simply take up the load, so Im not taking any great risk. As it stands now I should have moved to Stainless Chain years ago.
Hope that all helps and gives you something to ponder.