My 360 sounds like a sewing machine

Plymouth 65 said
Based on your information above you state 0.050 preload with stamped steel rockers. The statement that your exhaust valves sit about 0 015 lower than the intake valves. That should give you 0.035 preload on the exhaust lifters. I believe that should be enough but you may want to confirm with the lifter manufacturer. 65'

Yes that's correct, sorry if it was long winded. I am currently looking into it (PN JB-2225), but as far as I know they are a direct stock replacement and I cannot find any recommendation by Melling. I'll keep looking though.

mopowers said
What cam is it? Manufacturer?

A reground cam. Here's the cam info....it's pretty mild.