Gidday,
A rather complicated question but in summary.
Chattel Mortgages over older cars are very hard to get set, due to high risk over the condition of the vehicle, this should not be the case with Classic Cars but automotive finance companies generally just see cars as New, Demonstrator or Used.
General personal finance (often used for car purchases) is approved based on a range of pcriteria including financial capacity and credit history. Once approved you can use the money for just about any, legal, purpose.
Cheers
Pb