Sorry I found your post 3 weeks late.
How does Newtonville work for you? I have lately been going to The Newtonville Tailor; a small one-woman shop run by a Russian lady named Katya. She has some serious skill, recently completing a dicey shoulder pad surgery on a blazer for me without a hitch.
Very reasonably priced; cash only.
I have also tried Al's Tailoring in Watertown, and it was fine but he missed a few nitpicking details. Also more expensive.
Thank you so much, @Sal Paradise
Have you tried Marios in Chestnut Hill? After searching through this, that's the most accessible tailor from the list above (while the Pru sounds great, it can be a hassle coming from Weston, where I live).