Upgrading 7.2.4 to 7.4.1

Dear all,

I've got an old 7.2.4 DB which I hoped to upgrade to 7.4.1.
The old syntax used for creating tables had lines like
..
id integer DEFAULT '',

which translates to this error:

pg_restore: [archiver (db)] could not execute query: ERROR: invalid
input syntax for integer: ""

I found out that integer with '' as default is not acceptable after 7.3.
Also, some complaints were given with the data, particulary numerous
"\N" lines when restoring (this can be worked out by using -d switch
when dumping).

Also, schemas are not going to be created (some 7.3 documents gave this up).

Thus, must I update every DB creation script by hand and try to restore
only the data?

Regards,
Jarmo