I think you want a '65 trans for that type of conversion. Contact these guys to see if yours can be converted.
5061 E N County Line Road
Camby, IN 46113
From: Dave Dumais dave.dumais@xxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx>
To: yahoogroups <chrysler300@xxxxxxxxxxxxxxx>
Sent: Wed, Jan 13, 2016 4:34 pm
Subject: [Chrysler300] 64 trans. conversion?
Can a 64 300 -727 be converted to a "slip in" drive shaft yoke and boot for a non 300 application?
And, will the 64 crank shaft flange mate to a flex plate, even though it was a 4 spd. engine? 6 bolts on rear flange.