Old cars are old and often disappointing. My money would go on the Singer Porsche..taking something that was great in its day and modernising it in a thoughtful way so you get the best of both worlds. An Old Aston would be great…once it had been modernised in a similar way. The same goes for E-Types and anything of that era. The Sport Quattro is a beaut too though.
Depends on your frame of reference. Take something cheap like an MG Midget, yes even the last BMC engined ones will only just keep up with the average modern car to 60, and the older A series doesn’t stand much of a chance unless it’s been tuned. But then even when new it was pitched somewhat lower than the MX5 which some would say was it’s successor, it’s more like a Smart Roadster, which it will actually match to 60 (depending on the model).
Then take some of the exotica costing £500k, they mostly wren’t £500k cars when new (inflation adjusted). The DB4 for example was £85k in today’s money (£3950 when new). That’s a fancy BMW M3. It’s not meant to be a supercar.