I found/bought a PS3 original 40GB version at a garage sale for $10. Obviously it was broken, luckily I was able to fix it following the iFixit guide.
It went well. Was worried that I didn't spread the thermal paste evenly but I was able to play all of Heavy Rain sans issues.
Had to heat the board in the garage so the house wouldn't smell of solder.
The guide looks to be for either newer PS3s or the 60GB original model. My 40GB differed slightly in that there were no memory card slots (step 22-23) or control board (step 11/13). Also removing the heatsink fan combo took a little more effort than the video and I had to consult another source to make sure I didn't break anything. Used the spudger to go around the logicboard and pry the fan off.