You cant go over the limit of the health in pedstat.dat
The only suggestion I have for you is to do so in LUA.
Here is the code, for the script making stuff u can go to my LUA tutorial and DaBOSS's scripts in free roam tutorial.
Here is the code :
PedSetHealth(gPlayer, 9000)
If you do not want to start scripting then you will have to set your health to something under the limit.