your best bet is probably within the scrub python complex or the Morelia genus but idk how strict you are on the size parameters because while it’s a little rare, female black head pythons can exceed 9+ feet (and cost as much as a new car) - same thing with scrubs; while they’re likely to be 7-9 feet, it is quite possible and really easy for them to surpass that
with this being said, girth is an important thing to consider eg: my scrub python and my female mainland Burmese Python are the same length but because of girth, she makes him look like a rat snake - this being said, even with the girthier species like P. bivittatus, P. sebae, etc they still should be somewhat lean and “extreme girth” or rather, morbid obesity, is something which could be prevented thru a healthy, well balanced, moderated diet
best options i can think of given your parameters would be Centralian python (M. bredli), Coastal Carpet (M. s. mcdowelli), or Northern boas (B. imperator)
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