I've had a few Helianthus 'Autumn Gold" for 5 or 6 years now in an all-day blazing sun position in the poorest/rockiest/best-draining soil on my mostly clay property and they've performed admirably for me. Most of the more reputable resources (MOBOT, etc.) describe them as "tolerating a wide range of soil conditions", but generally preferring medium/mesic soil.

I think mine have stayed relatively compact (clumps of about 2-3' wide and tall) all these years because they're in poorer, drier soil, but I imagine they would likely grow beyond those boundaries in a moister area like yours. I think they definitely don't do well in soggy conditions, but as long as your new location is draining well, they should be fine!

I have had the straight species in alkaline clay for many years, and it has done well. How tall does Autumn Gold get? I had to get rid of mine because it got at least 8' tall, and as it doesn't get full sun all day, it was flopping all over the place. I have a pretty wild garden, but it was too wild even for me. I would love a shorter version, though not a true dwarf at 12" or so.

@gdinieontarioz5 'Autumn Gold' is known for being more compact and clumping than the species. As mentioned above, my clumps have never gotten more than 2-3' tall and wide in the 5 years or so I've had them (but they're in poorer, dry soil in all-day sun). With more moisture, I wouldn't be surprised if they grow beyond that (but definitely not as tall as the species).

I saw a more compact type in the Royal Botanical Gardens near here last year. If I ever come across one, it is going home with me.

There's an even more compact cultivar of H. salicifolius: 'Low Down' is reported to max out at 12" tall and 16-20" wide. It's also said to be less cold hardy than other cultivars, and doesn't reliably overwinter in z6 without protection: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=250001&isprofile=0&;