Very curious. You criticize the kit's gun barrel and suggest an aftermarket replacement. I've NEVER heard any criticism of its dimensions in the 24 years since this kit hit the market. Perhaps you're noting the smaller muzzle brake of the late Tiger I. IIRC, this kit gives you options of both the late and the early muzzle.
BTW: "casting" is the incorrect term. These are injection molded kits so the descriptive term you want to say is: "they were molded well." Casting would be fine for resin or cast metal parts.