Mega and SPI for SSD1331

Hi,

I have a Mega and SSD1331. I would like to use the Adafruit LCDGFXDemo to test the display, but which pins should I use and declare? Do I have the following correct?

/ You can use any (4 or) 5 pins
// hwspi hardcodes those pins, no need to redefine them
#define sclk 51
#define mosi 50
#define cs   53
#define rst  9
#define dc   53/code]

 Also when I try to upload to my Due, I get the following error;
[code]Arduino: 1.8.10 (Mac OS X), Board: "Arduino Due (Programming Port)"

fork/exec /Users/********/Library/Arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1/bin/arm-none-eabi-g++: no such file or directory
Error compiling for board Arduino Due (Programming Port).

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
/code]

 I've installed the addition IDE and selected the Due Programming Port?

Dizzwold.