Give us some more to go on!
What are you going to do with it? How much will you drive it? Where will you drive it?
Series vehicles are EXTREMELY basic. Not many can drive one as an only car... I assume you already have at least a 90 to drive?
Very harsh suspension, unless you go for parabolics,very noisy, especially the diesels, wander a lot on the road, so you have to concentrate, lots of rattles, crashes, bangs, clangs and shakes. Leak like a sieve, useless heaters. Lots of rot, dodgy wiring (I've had 3 electrical fires in mine before I rewired it).
But I love mine!! It's a 1960 Series II SWB Hardtop 2.25 petrol. It's had a chassis-up rebuild, galvanised chassis, galvanised bulkhead, galvanised rad panel, Turner engine, Whitehouse gearbox, Autosparks loom, parabolics, PTO drum winch, twin 75 litre fuel tanks, Wolf wheels with 7.50x16 General SAG's, no heater (just put a coat on).
I use it mainly for greenlaning and trips to the council tip. I drive it maybe 3 times a week, mainly short journeys, although there is a plan to go to Morocco for 3 weeks in it. Watch this space.
In terms of versions to go for, the most practical are the SWB's, and the most practical of those are the Safari's (Series II's and III's), with a rear door, 7 proper seats, and slidey windows in the rear, and that lovely double-skinned roof with it's vent bubbles.
Other than that, have a look at a few, go to some shows, and try to drive a few. Then make your choice!
Effortless.