Best Route for a Cross-Country Road Trip?

[ref1655]

not a bucket-list objective but more out of curiosity...a buddy & I have been toying with the idea of driving across the United States sometime after Labor Day.

1. the departure point would be either: (1) SF or (2) LA.

2. the vehicles of choice are: (1) a 1959 Corvette (283/fuel injected); (2) a 1957 Porsche Speedster; or (3) a 2014 Subaru Outback. concerns have arisen regarding parts availability & the quality of out-of-state mechanical repairs on the two older vehicles (if needed) + their lack of air-conditioning & overall storage space. on the other hand, while the Outback is far more practical from a common sense standpoint, it lacks a certain 'allure' for a journey of this nature.

3. if leaving from the LA area...the Corvette or Speedster would be driven. from SF...the Outback. based on these two hypothetical starting points, a S/E route or a N/E route are to be considered ending somewhere on the east coast.

4. after arrival, the car would be shipped back to CA (knocking on wood that it arrives in one piece).

so the questions are...which car would you opt for & what would be the most interesting & safest route? time constraints are roughly 10 days/shared driving with evening layovers at a roadside motel. would also like to avoid any potential or upcoming seasonal bad weather. lastly, depending upon departure point, where on the east coast is a good place to end this journey?