I don't think they are to resemble people from the game. wong looks more like an indian and king henry is smiling. beruga seems quite fitting, maybe in his early years. but it's an interesting theory though, it might be they resemble some other people the programmers liked or sth.
There are enough hints to lead me to believe that they are the three (again, not necessarily in that order, I think Wong is actually the second one)
Mostly how the story seems to tie them in. Wong mentions Henry and Beruga, the password in Beruga's lab, a reference someone mentioned linking Henry to Bloody Mary
I can't see any resemblance between the portraits and any characters in the game, but since the first time I saw it I thought the one on the right looks like Jeff Foxworthy.
After taking another look the 2nd guy on the left resembles one of the villians from The Princess Bride. It's been so long since I saw it I can't remember the actor or characters name, but he was the one who ended up being poisoned.