I was unaware of the 3D model.
Specter understands what is wrong with Rowland's description of the man and basically fillets him over his description of a man standing in a window with the window sill being located 14 inches off of the floor and an opening of 2 ½ feet above that. Rowland’s description never matches those dimensions and the whole port of arms thing becomes confused. He does not seem to know any of this, and I think that is why they were asking him if he had ever been in the building.
Spector did ask a lot of questions, and, after testing some of the answers with my 3D model, I felt Rowland got things right. That and the fact that Rowland said something to his wife at the time (before any shots were fired) and his 11/22/63 affidavit seems legit. I cannot say the same about his later embellishments regarding the elderly black man though.
Here's a view of the west windows in the 3D model from Rowland's viewpoint:
The figure is about 5' back (north) from the inside of the south wall. Please ignore the missing window in the western most opening, my model is constantly being altered and I just have it invisible at the moment. The rifle is there, at port arms, but a little hard to discern due to the dark suit of the figure. Remember that Rowland said he had on a light colored shirt, possibly a tshirt.