As you say 'base for a track car', then surely (budget dependant) any of the 172's or 182's would do?
Weight can be saved on each one, power can be gained on each one, suspension etc can be changed on each one.
Unless I am missing the point, as it is just a base/start, then would a decent ph1 not be the obbvious choice? It is cheaper and can mean more of the budget can be spent elsewhere.
From what I have seen, the 172 Cup's seem to be relatively expensive, I wouldn't pay more (than a similar age/condition 172 non cup) for one.