That would be tremendously tough, as the original auto (it was 'TwinTurbine' starting in '59, but it's still a DynaFlow) doesn't shift. It has a planetary low gear, but placed in drive it doesn't shift at all, it has variable stator blades that change the 'ratio' as it accelerates. RE it being a 4-dr; in general the opinions here are correct ('fine as a cruiser, not so great for resale') but take note of my observation. I've got 20 years in the BCA and 25 years owning my B-59... Buick guys have no problem with 4-drs, esp in this era. I've not encountered such a high acceptance of 4-drs with another marque like I've seen with Buick. Maybe that harkens to the supposed 'older' crowd that frequently likes 'em, I dunno. Looks like a super sano ride, hope you work out a deal & enjoy it!