225 Slant 6 to 3.9 V6 conversion?

I had two Dakotas with the 3.9. The engine is a 360 with two cylinders lopped off. Same bore, stroke, etc. That being said, I would not put one in an A-Body. I could never get any decent mileage out of either of them, could not break 20mpg. If it were me and I wanted more power I would go ahead and put in a 318. For the difference in fuel mileage you might as well, it couldn't be more than a few miles per gallon difference. Just my two cents.....