I hate to discourage you, but I have seen the seals replaced in two pumps, I did not do them, but I know of them.
In both cases, the seals did not hold. These pumps are normally durable. You may be better off putting on a used pump. I put on a used pump some time back and has not leaked.
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in