BAS, can't tell you how MUCH to invest. But I would submit that given the two teams involved, it's really, really hard to make a case for the Lakers being the Undervalued team on the Series betting price.
Thus leading to a reasonable conclusion that the Orlandos are at least a modestly Undervalued team and +220 is a reasonable place to at least make a "regular sized" investment.
I've actually just done $50 so far and am hoping it might climb by Thursday evening.