built up 318 oddly low MPG's? hp rating?

WOW! haha gone for one day and all my problems have been answered lol, thanks guys. Let me see if I can answer all of your questions, I'll just go down in the order you guys replied. I'll upload some pictures of the engine too.

-I don't know how far down my pistons go

-I was told they were 360 heads and I think the machine shop confirmed that, it was a year ago but I think it is safe to assume they are 360 heads.

-I think it is just a stock converter, it is a basic 727 automatic 3 speed.

-it has a 3.55 posi in the back yes I have a tach gauge no vacuum gauge. 60 pmg on the freeway is 3000 rpm's

-it smells a little rich ya but nothing awful, here are the cam specs
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=626&sb=2

-This last fill up I was careful to keep my foot out of it because I wanted to see the best I could get, I nailed it twice the whole time. other than that there was an egg under my foot.

-I def. will keep my vacuum advance hooked up

-I can get a MSD 6al box for $100 but im not sure I need it. cant help mpg's THAT much.

-I drove it the whole time with a messed up kickdown until about halfway through this last tank. it just would go to like 45mph before shifting to 3rd or me letting my foot off, so I could see that helping my mpg's a little but im still wanting like 14mpg haha

-I primarily drive freeway, not like 60mph at 3000 rpm, but like the 50 mph country roads with stop signs and such.

-no I have not done a compression test yet

-the 650 is a mechanical secondary