Sounds like the "Reptile Man" really isn't going to know for sure about the history on this little guy. No offense, but it isn't likely he'd know or that anything he might be able to tell you would be reliable. Even so, your baby is great and you're going to love having a boa - they are awesome!
You won't be able to tell whether he's a 'he' or a 'she' from the anal vent. Some snakes have more significant spurs than others whether they're male or female. The only way to know 100% is to pop or probe. If you know a reputable expert near you, they might be able to show you how (NEVER try to pop or probe without an expert to show you how - you can hurt your snake if you do it wrong). That is, if it matters to you to know for sure.
Just to be clear, I wasn't ruling out any of the locals - that's why I said "whether he's Guyanan or Surinam or some other local..." And you're right - he could be a "mix." Without documentation from the original breeder, it's impossible to know for sure.![]()