283 heads on 350

[cppursell]

I have a '67 1/2 ton chevy truck with a 70's 350 engine, with #3973487 heads (they match letter "K" on this guide: http://fastnuf.com/Headguide.html). I love it, but I hate the mileage: 11 mpg. My goal is to get better fuel economy. My cousin Jim has experimented with several small block engines and says we can put heads from a 283 engine onto mine. He has successfully done so on a 350 of his, and has been driving fine with no pinging. He reports a compression of 11:1. My cousin also has a 307 in one of his trucks with 283 heads, resulting in a 10:1 compression; according to him, that truck gets a minimum of 15 mpg. (those heads match letter "B" on above guide).

Would installing 283 heads onto my 350 be a good idea? What other tips do you have for me to maximize my fuel economy? Thanks for your advice!

P.S. Other info that might be handy: Turbo 350 Transmission, 3.54 posi rear, engine timing is set at 7.