I feel that cold setting it back to 135 mm should be fine. Are you familiar with the string method of checking for symmetry? Sheldon Brown has an article.
You can just go further with the threaded rod method - which is handy because you can count turns and work methodically. I like the plank method myself, a little more brutish but you can bend each side separately and achieve symmetry.
Rad bike.
I feel that cold setting it back to 135 mm should be fine. Are you familiar with the string method of checking for symmetry? Sheldon Brown has an article.
You can just go further with the threaded rod method - which is handy because you can count turns and work methodically. I like the plank method myself, a little more brutish but you can bend each side separately and achieve symmetry.