baseball4lf8

I have a 67 coupe with a 289. I want more bottom end perfomance and have asked many people what to do about it and it seems everyone has a different opinion. Right now the car has a 650 holly and a torker 2 intake and a big cam. This is the way the car came when i bought it around cristmas time. i dont know what gears are in the rear end. Its pretty slow off the line so im guessing the're pretty numerically low. One guy looked at it and said it was an 8.8in and another said it was less than an 8in (he was a chevy guy though). I didnt think ford ever made less than an 8in rear. Anyway, i was going to choose between a new posi rear end with 3.7 gears (are there any 8in posi units?) or an edelbrock performer power package. I was going to get the carb, cam, and intake package. the package and install is about $900. I was wondering how much the install for a rear end is? i was looking at the eaton rear which is about $420. So, should i change the rear or engine parts to get more bottom end power?