I'm sure there's some model Hammonds that have spring reverb
Yes, and also some Leslies.
If you are trying to build a complete and accurate simulation, the spring reverb effect of course has to come before the in-the-room Leslie effect... it is the only way it could have been done. That's not a judgment on how musically desirable it is or how many people will ever want to use that combination, but for accuracy, it makes sense for it to be there.
Reverb after the Leslie doesn't exist in the real thing except as the actual room reflections from the room the Leslie happened to be in (or whatever effect was added in the studio). And there are plenty of plug-ins for simulating whatever room you'd like to put it in (or whatever studio reverb effect you like). I don't really see great purpose in building room simulations (or studio-style reverbs) into a hammond/leslie emulator. I guess maybe a simple reverb effect for convenience. But a proper external reverb sim is really a whole different animal, with lots of variables of its own.