DIY Gamer Conversion

So I've re-flashed as suggested (thanks for step by step guys) which all went well, and have updated the code to as follows:

var OE = B6;
var CLK1 = C6;
var CLK2 = C7;
var DAT = C8;
var LAT = C9;

var HIGH = 1;
var LOW = 0;

pinMode(OE,   'output');
pinMode(CLK1, 'output');
pinMode(CLK2, 'output');
pinMode(DAT,  'output');
pinMode(LAT,  'output');

var counter = 0;
var currentRow = 0;
var image = new Uint8Array(8);

var display = [
  [1,1,1,1,1,1,1,1], 
  [1,1,1,1,1,1,1,1], 
  [1,1,0,0,0,0,0,0], 
  [1,1,1,1,1,1,1,1], 
  [1,1,1,1,1,1,1,1], 
  [1,1,0,0,0,0,0,0], 
  [1,1,1,1,1,1,1,1], 
  [1,1,1,1,1,1,1,1] 
];

var S1 = new SPI();
S1.setup({mosi:DAT, sck:CLK1, mode:3});

var S2 = new SPI();
S2.setup({mosi:DAT, sck:CLK2, mode:0});


function updateDisplay()
{
  var newImg = new Uint8Array(8);
  for(var j=0; j<8; j++) {
    newImg[j] = 0x00;
    for(var i=0; i<8; i++) {
      newImg[j] <<= 1;
      newImg[j] |= display[j][i];
    }
  }
  if(newImg != image) {
    for(var i=0; i<8; i++){
      image[i] = newImg[i];
    }
  }
}

function updateRow()
{
	if(counter==8) {
		counter = 0;
		currentRow = 0x80;
	}
	writeToRegister(0);
	writeToDriver(image[counter]);
	writeToRegister(currentRow);
	currentRow >>= 1;
	counter++;
}

function writeToDriver(dataOut)
{
	digitalWrite(OE, HIGH);
	S1.send(dataOut);
	digitalWrite(LAT, HIGH);
	digitalWrite(LAT, LOW);
	digitalWrite(OE, LOW);
}

function writeToRegister(dataOut)
{
    S2.send(dataOut, LAT);
	digitalWrite(LAT, LOW);
}

updateDisplay();

setInterval(function(){
  updateRow();
}, 1000);

(Just put a 1s interval for now to test) but I get an error in the terminal window:

INTERNAL ERROR: Timeout on SPI TX
INTERNAL ERROR: Timeout on SPI TX
INTERNAL ERROR: Timeout on SPI RX
at line 2 col 25
    S2.send(dataOut, LAT);
                         ^
in function "writeToRegister" called from line 6 col 22
in function "updateRow" called from line 2 col 13
in function called from system
ERROR: Error processing interval - removing it.
Execution Interrupted during event processing.

@DrAzzy I'd love to see your write up if you get that working.