Ive never seen a L which hasn't had reclining seats. As the L was a 'luxury' model of the F it had reclining front seats, seats and doorcards had vertical lines rather then being plain, carpet instead or rubber flooring, updated rectangular speedo, dashboard cover, black steering wheel, column mounted steering lock/ignition, centre tunnel tray, nudge bars, different front and rear badge and different hubcaps.
The 500R would be a good option as ChrisRlewis says if you wanted to keep the painted dash and round speedo, another bonus is they 600cc engine, but they are all left hand drive.
The heater system on all 500's is the same, ducting from the thermostat engine cowling running uner the car through the centre tunnel and up to the windscreen, controlled by a flap behind the drivers seat. Also 1 flap either side of the glovebox/undertray to direct air to either footwell or windscreen. The system works quite well when warmed up but can smell a bit if your engine isnt in great shape