Excluded from private school

To my knowledge exclusions stay on permanently. Schools should pass the record on and rightly so.The new school should know what to expect.

Just a word of caution though, if you think there are more resources and time in a state school to deal with a child who gets violent then you are very wrong. There are more children often eith a wider range of needs, not enough TAs and pastoral staff to go around and often class sizes are bigger.
Equally, a state school isn't going to be more tolerant of violence than a private school (other than schools with behaviour problems already so they are used to it but hate it).

The likelihood is that if he displays the same behaviour in a staye school then the following will happen:
Fixed term exclusions
Managed move to another secondary school (if it works he stays there if it doesn't he goes back to state school 1)
Reduce timetable and have him educated off site for some of the week.
Longer term provision at a pupil referal unit
Permanent exclusion leading to permanent PRU education.

I don't know if private schools share information, I know that in a state school if we have a child move to the private sector we send all information and records over. Hopefully someone will be along to give you more information shortly.
Hope you manage to resolve this, as a parent of a child with ASD it's so frustrating trying to get them to understand the consequences of their actions and to help them manage those high emotions.

They won't be wiped from his record as far as I'm aware. We declare all exclusions (temporary and permanent) and receive the same from private schools.

Why is he fighting?

Are you addressing the root of the behaviour rather than foisting him on another school?