Thats the 2nd gen surf you are looking for. Up until 93 I think, you can find 2Lte version. 94 to 96 (before the 3rd gen) is 1KZ. 2L would perhaps be a little more fuel efficient than a 1KZ, but that comes at a trade off for torque. On the internet, you'd find numerous forums saying 2Lte is prone to cracking heads. A similar issue was reported for the early generations of 1KZ for cracking combustion chambers also. For petrol variants, there was the 2.7 lit and the 3.4 lit 5vz. A lot of people claim the 2.7 to be under powered (no personal experience though). It eventually boils down to the purpose you need the vehicle for. For highway drives / off road / towing etc. bigger engine would be preferred (with a manual tranny). Daily commuting / stop and go traffic would call for a smaller engine with auto tranny.
Since its a 25+ years old vehicle, you'd be lucky to find a vehicle with properly operating electric shocks. A set of those touches about the same price as the ARB / Ironman upgrade kit. On the other hand a set of replacement shock absorbers without the electronic control is fraction of that price. Therefore, people either upgrade to after market performance kits or the cheaper but original w/o electronic control shocks (guilty).
Since its old, and a Toyota, there will be a lot of vehicles with swapped engines. If the engine is swapped I'd prefer it was swapped with the same model. 5vz on a 2L frame, for instance, is adha teetar adha batair. Bolt on swaps are still kind of manageable IMHO.
SSR-G is the upgraded variant. I do not know the EXACT differences between the two.
Oh, the driving position of surf is different than other SUVs. A lot of people find it weird. So test it out first.
Happy hunting!