Double breasted is hard to come by, but I'll keep an eye out. Who knows?  Maybe the style will come back? ;)

In the meantime, & I know this is for G9, but the newer templates generally work well with other figures.

https://www.daz3d.com/dforce-padrino-outfit-for-genesis-9

The only other double breasted item I've found is:

https://www.renderosity.com/marketplace/products/86457/zoot-suit-for-m4

I export out to Lightwave, BTW. And as I was writing this and going through the steps I thought I took exporting out of DAZ before to explain the issues I was having, it worked this time. Mostly, except by the wrists and toes, but the geometry is clean enough this time that I can easily fix those. 

What's the other M3 Suit you have? This gives me encouragement.