I have a stock rebuilt 5.2 in my 1500 truck does anyone sell 1.6 rockers for magnum heads and do you think it will improve performance or gas millage in anyways

well..the stock rocker ratio on a magnum is 1.6

so you are already there..

Everyone steps up to the 1.7:1 on the Magnum engines, as "1.6:1" are factory/stock.

There have been posts here on Moparts in the past,
{by Jesse Lackman, perhaps?}
stating that although the official factory spec for Magnum rocker arms is 1.60
if you actually measure several with a dial indicator,
they average a 'real world' ratio of about 1.67 or greater.

In the 'Magnum Manifesto' three part article series in Hot Rod magazine back in 1998, it listed the rocker arm ratio as 1.65,
and that article appeared to have a lot of input from Chrysler's Engineering department back then.

get the cam reground by bullet cams, using their HR259/316 lobe for both the intake and exhaust. use hughes #1110 springs, and their retainers.

on the cheap, cut the runners in the intake down about 2" internally, on the not so cheap, go with the hughes/edelbrock RPM air gap conversion.