An R Code 62 is not held with the same reverence as the R code that followed in 63 1/2 when the 427 came out and this is the reason why
"R 8-Cylinder 390 Cubic Inch 4-barrel Low Compression Export, 84 Octane"
The above quote is from the 1962 Galaxie Registry.
The following is a list of engine codes for all HiPo cars of which the 62 R code is clearly not a HIPo car.
The HiPos all had bigger brakes, large fuel lines and fuel pump, hard brakes lines going up to the radiator cross member, the suspensions were upgraded. They were all manual cars, power steering and power brakes were not an option due to the low engine vacuum.
B 8-Cylinder 406 Cubic Inch 4-barrel High Performance
G 8-Cylinder 406 Cubic Inch 6-barrel (3 deuces) 405 hp
M 8-Cylinder 390 Cubic Inch 6-barrel (3 deuces) High Performance 401 hp Q 8-Cylinder 390 Cubic Inch 4-barrel High Performance 375 hp
R 8-Cylinder 390 Cubic Inch 4-barrel Low Compression Export, 84 Octane
Am not sure any of this helps.