I found an old english recipe for "iced box cake" the filling is raw egg, sugar, butter & fruit. do you think the meringue powder will do the job?

It may, but I am not sure.

Most grocery stores sell egg white powder ("Just Whites" is the brand name I saw in my local store) They have instructions on how to reconstitue the powder to make liquid egg whites. It can be found in the baking aisle.

I have also read that some stores sell pasturized egg whites. They may be somewhere in the dairy section. ---- just too lazy to look for these.

HTH