23XI Racing announced that Corey Heim will pilot the No. 50 Toyota in the Ally 400 at Nashville Superspeedway on June 30. 23XI, which fields two full-time entries in the No. 45 (Tyler Reddick) and No. 23 (Bubba Wallace), will field a third for Heim to race in. The No. 50 car is set to be sponsored by Mobil 1. Heim made his Cup Series debut at Dover last month, filling-in for the injured Erik Jones in the No. 43 Toyota for Legacy Motor Club. He finished 25th at Dover and 22nd at Kansas this past Sunday. The 21-year-old prospect has seven CRAFTSMAN Truck Series wins, two coming this season at CO…