For pre-war Martins, I would say Blazer and Henkes and Laurent Brondel do a fantastic job. Circa, too.
Bear in mind, pre-war Martin encompasses a WHOLE lotta sound. I’ve had a chance to play many, many pre-war Martins. And, in one case, two 1930 OMs side by side. Very different guitars.
The B&H OM-28 I played last year is a dead ringer for OMs I’ve played in the shop at Schoenberg.
http://om28.com/ProductDetail?product=P191106001
My Brondel OM-42 as well. Circa is a little more of an evolved form of that sound, as Bob Berger put it. More power and headroom with a little less bass. Slightly different sound. I’ve played a bunch from various other guys, but those are the ones that have come the closest to catching the overall vibe.