My preference would be a 1967 B with OD. I love the early dash and cranked shift lever of that model. But I'm not sure the OD trans had the cranked lever.
OD did not have the cranked lever from the factory, as far as I can remember this early in the morning.
Wingtip -- there are a couple of things that seem to be popular with MGB folks.
Overdrive
Metal dash (up to '67 for USA cars)
Chrome bumpers (up to early '74)
The later chrome bumper cars (late '67 - '74) had a stronger all-syncro gearbox compared to the earlier 3-syncro box. Many parts exchange from year to year so you will find that quite a few cars are a mix of parts. My '70 (UK home market RHD car, so it's a bit different than the USA cars) has an earlier style grille and an early style aluminum bonnet that were both swapped in at some point. Some early cars have had the later gear boxes added (requires a bit of hammering in the tunnel for clearance). Few USA market cars had overdrive as standard, but many now have had it added in.
The earliest MGBs had a 3-main engine, which changed to a somewhat more robust 5-main engine in '65.
Some argue that the late '67 MGB was the best in the USA as they were the only ones with the steel dash and 4-syncro gearbox. Others prefer the shift feel of the earlier transmission.
You'll also have a choice between wire wheels and steel wheels. Get a car with the one you want, as it's a bit complicated to switch from one to the other.
A good reference to pick up is the
Original MGB by Anders Ditlev Clausager -- it lists all the various changes that happened through the years.
When I was searching for my car, I made my list of necessary features and held out for all of them (RHD, disc wheels, overdrive). They made a half million MGBs all told, so there are plenty out there. Were I looking for a LHD car, I'd pick a '65 - '67 car with disc wheels and an overdrive.