Is there a breed club or society?
Although it's still worth going through them for breeder recommendations, the Boston breed club doesn't appear to be that great in terms of being open and honest about health. The only health issues they mention on their site are the two types of cataracts the breed can suffer from and luxating patella. Nothing about BOAS, hemivertebrae or LGMD.
The French Bulldog Club are much better in that regard and run their own reasonably good health scheme, however uptake of it hasn't been that great. I've just had a look at their published results (updated a month ago) and there are less than a hundred dogs who have attained the gold award.
The gold award requires dogs to have been graded for BOAS, had their nostrils graded (personally I feel the club is lax in allowing dogs with poor nostrils to pass given the high correlation between pinched nostrils and BOAS), been pronounced clear of heart murmurs by a cardiologist, had their patellas checked, been DNA tested for hereditary cataracts and degenerative myelopathy, and to have been screened for hemivertebrae. To me this is the absolute minimum any Frenchie breeder should be doing, as well as breeding for much more moderate features, all the health testing in the world isn't going to help if the breed still has no face. There are another couple of DNA tests which breeders should be utilising (congenital hypothyreosis and cystinuria) as well as those prescribed by the scheme.
Like Bostons they suffer with a very high propensity for needing c-sections, over 80% of Frenchie litters aren't self whelped. Similarly, the reason for this is the shape they've been bred into and it's another reason why breeders should actively be breeding away from current conformational trends.
FBs are much better off in terms of genetic diversity, with an EPS of 132.28 and an average COI of 5% however breeders still need to be aiming to maintain that diversity as much as possible.
In the last ten years there's been a massive upsurge in the numbers of Frenchies being bred. In 2007 only 692 were registered with the KC, in 2016 the number registered with the KC was 21,470. Unfortunately for the breed a pretty high proportion of FB breeders are doing so to capitalise on their popularity, knowing that people will still fork out thousands for a pup even with no health testing or anything else in place. There's also a huge trend for producing non-standard colours (which then sell for silly money) with little consideration given to anything but the colour of that dog and the colours they could potentially produce. It's not uncommon to see kennels clearly spending considerable amounts of money on DNA testing for colour but doing very little health testing 
As well as approaching the breed clubs I'd actually also suggest joining the CRUFFA FB group if you're interested in getting a puppy of a brachy breed. There are a number of breeders in the group who (despite the frequent ire of supposed breed enthusiasts, often breed club members) are doing everything they can to breed consistently healthy and far less exaggerated individuals whilst retaining breed character and enough type to be recognisably Frenchies/Bostons/bulldogs/etc.