Being in Canada, I opted to get a new short block shipped up since my OE had low comp. I went this way for a few reasons. No one up here other than a few shops really know just what the fuck is going on. I had about 6-8 refurb'd engine emails ghosted because I asked simple questions like 'this is an mzr block right', 'which machine shop did the work', 'is there any numbers, blue prints, spec sheet?'. Nada.
Friendly heads up, AFAIK I bought the 4th last short block from Mazda USA and that was pre covid shutdown. They also have free shipping and that seems to include cross border shipping. All bonuses for me. That was the other reason why I didnt send my motor out - dont trust Canadian shops or dont know which machine shop to use and didnt want to deal with brokerage fee's and firm's or the crating it up and back n forth.
My MLC or mid life crisis keeps getting delayed so with the original short block motor being swapped out right now, if I want to live the dream in the future, I'll send that to Sp33d P3formance to be reworked and perhaps pick up a rebuild only ms6 and then I'll have 2 heads and 3 blocks. Or just remachine the head again to fit built block. These can be your dreams too!