I gave it a try and just use tiny as instructed don't worry about what shsh files it displays because you are not going to need them anyway. If like a number of us if you get the 1013 error you are set. Just leave the phone as is and greenpois0n it back to 4.2.6.
Make sure you have downloaded the 4.2.6 so you can point to it when tiny request that you select the firmware you want to restore.
NOTE: I did it twice with same result: Downgrade to 4.2.6, yes I actually upgraded the phone to 4.2.7 each time first and deleted the local folder files where I was saving the shsh files.
Keep us posted on your experience.