No. It will do absolutely nothing for you except cost you some coolant and another thermostat.
With an unheated intake manifold, the coolant temperature doesn't affect the air charge temperature much at all (certainly not in proportion). And it won't buy you any cooling capacity -- an open thermostat is an open thermostat, regardless of what temperature it opened at. The effect on pinging is very minor, FAR less than the fuel grade. (15 deg is insignificant considering that pinging occurs above 1200 deg F, and it's being driven by dynamic pressure waves created by in-progress combustion)
It's not enough difference to break things (like a 160 deg thermostat is), but it will also give you no gain. If it ain't broke, don't fix it.