For an old, adult snake with that established attitude it's likely to be difficult. This is a great example of a snake which doesn't suit the standard advice everyone will give you (keep persisting with handling until he gets used to it). The standard advice is most of counterproductive in these cases, as I described above, and in the mean time the snake is being traumatised and you're being frustrated and bitten. It will occasionally work, but you've already tried and found it not to (which is what you'd expect 9 times out of 10 in a case like this), so it's best to go with what's more likely to work.
Stop handling. Reduce interaction to the minimum you can. If there's anything which upsets him (going near the cage making him react fearfully, picking him up to clean the enclosure, whatever it might be), don't do it, or do it as little as possible. Now the big monster (you) has stopped trying to kill him (gently interact with him). Hopefully over time he'll get used to you and lose fear, now that you're just a part of the scenery and not something which tries to kill him. Then you can very slowly start to increase interaction. To do this properly takes a lot of effort and understanding, and to gain the experience which would make it easy, you'd need to work with a lot of snakes for a reasonable amount of time, and by then you wouldn't be interested in taming a snake like this anyway. In reality, a snake like this is best off with someone who will treat it like most people treat fish - look but don't physically interact. If you're happy to do that, great, and that's also the most likely way to get him to change. You might find that in a different person's care, the new person's attitude and different style may quickly or even immediately calm him down, and if you're going to get him to change, you'll have to change yourself. If you do have your heart set on an interactive snake, you're probably better off finding this one a new home. Probably a difficult snake to rehome though; people like me who can do it won't generally want to, and people who would want to generally can't do it. Whether you keep this snake for a short time or long time, cut out the interaction for the foreseeable future, and never opt for any interaction which is at all stressful to the snake.