I bought a used 292 engine that I put in my 56 customline years ago and when I checked the rocker arms they were mixed between high ratio and low ratio . A guy at a swap meet says that you only need the intakes to be high ratio not the exhaust. Is that true or is that not a good thing to do?  Any thoughts?

Want & "need" are two different things. All Ford/Mercury Y-block engines use the same size exhaust valves. Apparently, the exhaust flow is such that larger exhaust valves weren't needed. However, Ford used 1.54-ratio rocker arms for both intake and exhaust valves in 1957. 

If you have a stock engine, it was equipped with 1.43 rockers. You won't lose anything by using 1.54 rockers on the intakes and 1,43 rockers on the exhaust. 

Assuming you have eight 1.43 rockers and eight 1.54 rockers and also assuming the valve springs are adequate in their installed pressures, you can expect a performance gain by using the 1.54 rockers on the intake valves.  Not only does the lift at the valve increase with the 1.54 rockers, but the amount or duration of valve opening also increases as it starts earlier and closes later.  If the valve springs are marginal in their pressures, then the 1.54 rockers would go on the exhaust valves as the exhaust valve float would come later in the rpm band than if installed on the intake valves.  The weight of the valves and the valve spring pressures must be taken into consideration when increasing the rocker arm ratio.

Lorena, Texas (South of Waco)

Thanks for the information. I always like a little more power but it really isn’t necessary. My 55 Crown and my 56 customline both with 292 s have plenty of power .now if I can find a Time Machine and go back to the late 60s and early 70s my Y powered cars would have been so much better with what I know now .