by the way, putting bigger heads on there ain't going to do much without headers, a different cam and some bottom end work. you can pull as much air in as you want but if the motor can't use it then it's worthless. but if you plan on stroking it or something later down the road then bigger heads can help when you do that.
Ok folks I got educated awhile back. Ford built a 370 (I hope I got that right) truck engine based on the 385 series. If this is what he has and NOT a 360 FE it very well could have 429 heads. I suggest you post pics of the engine in question or at least the valve covers. The bolt pattern on the valve covers should answer the question.