Throttle body mod?

Hi,I was wondering if anyone could tell me what size and brand of throttle body I should use in my 1993 CVPI.I'm installing another engine in her(same 4.6) cuz the original is just tired.I've been told that the throttle body will give me more horses and better mpg.I'm guessing the one on there now is the original and I dont know what size it is or what size I need for best performance.Ive also been a spacer is the way to go.Keep in mind I'm also installing headers if that makes any difference.Any info is greatly appreciated,thanx guys

Check her out http://www.cardomain.com/ride/2464923