If you're even thinking of doing it to a sedan you need major reinforcement on the B pillar so closing the driver's door won't result in bending the B pillar inwards. Coupe -> converible conversions don't have this issue, there's no B pillar, so the rear portion of the car reinforces all of that. In a T-Bone crash, a moderate hit to the doors will probably result in death.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k