I had one just like that, Ember Glow they called that color. Mine was a 390 4 speed. Originally a 2BBl car ... I installed 428 CJ heads, cam and intake which made nearly identical to the GT. No traction bars though and man did it have a wicked wheel hop with those rear leafs!
GT had the 390. 500 had a 289. 351 is an upgrade. 400 hp is jus about right. Although grill is not chrome it is aluminum. I had a 67 289. Beautiful cars.