Cool build. Well built and finished. I built this kit a few years ago and also found that the tires sat too deep inside the body. So I cut new longer metal axles from music wire.
That body is in pretty bad shape. Perhaps you are better off converting Jimmy Flintstone's resin 1958 Chevy sedan delivery body to a wagon. Resinrealm.net sells a 1958 Chevy Yeoman 2 door wagon that can be converted to a four door. Good luck!