People have been modifying cars since the day 1, it's in our blood.... Seeing people posting about roll over protection or other features that new cars have makes others think our cars belong in a museum and not on the road, and is a killer to our hobby regardless is you like stockers or hot rods. I have had people ask me if I feel safe at 70mph in these old cars or state driving an old car is a risk to others. Let's not perpetuate that talk or it could find itself legislated.
These cars will handle 60-80 mph just fine on stock suspension, brakes of the era should be upgraded but I have driven 30's cars with beam front axles for hours at higher speeds and they do just fine. All my cars have disc brakes... If you're scared to push the envelope a little, maybe take up something safer like knitting
Oh, and I would drive that 37 DeSoto conv at 80mph all day with suspension that's not worn out and disc brakes. Maybe shim the axle a little to add some caster too....