Problem with GTB sys1 boards is mainly the spider chips.. these have been obsolete for years. The boards themselves were not diode protected and so a locked on coil etc would wash right up the line and fry the chip. Every other component on these boards can be sourced which makes them repairable so long as the spider chip isnt fried... if you manage to get it going then make sure you install some diodes to protect it...

I have a blown sys1 board here... bet the CPU chip is the one thats fried though