I believe you mean R9 270x but yeah, it will run GTA V fine at 1080p, 60fps on high, maybe with some tweaking. And here's the best mobo I could find around your budget:
PCPartPicker part list:
http://pcpartpicker.com/p/m7Z6XL
Price breakdown by merchant: http://pcpartpicker.com/p/m7Z6XL/by_merchant/
Motherboard: MSI 970A-G43 ATX AM3+ Motherboard ($56.98 @ Newegg)
Total: $56.98
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-07-24 17:12 EDT-0400