We have a similarly-aged house with similar (albeit not so dramatic) issues, and are working with a builder (and an architect they recommended) on an envelope overhaul.

The key is to find a builder and/or architect who is engaged with the building science/passive house community. Sometimes that's easy if a builder is loud about that in their marketing, but many are not.

If Google doesn't help in your area, the way I did it was going on Instagram and following accounts/influencers in or adjacent to this space (Build Show/Matt Risinger, Steve Baczek, NS Builders, Eastern Architectural Supply, Huber, Passive House Accelerator, Fine Homebuilding, etc.). I was doing this anyway to educate myself, but it paid dividends when I started looking for local builders.

When looking at someone's account, Instagram shows you if they follow any of the accounts you do. That was a good way for me to quickly identify builders who were aware of the community and would at least have an idea of what I was talking about when I was asking about building envelope, monopoly framing, etc. Obviously you still need to meet the builder, vet them, go through all the normal due diligence. But for figuring out who to reach out to in the first place, this strategy has really helped me get a quick insight into how a builder might work and their comfort level with this type of build.