If it was done properly, I'd prefer that it was already done. The 80 series landcruisers (particularly the later years, 96 and 97) have been prone to head gasket failure. The head gasket design was subsequently modified and improved to prevent this. I'm unaware of anyone with the replacement head gasket, having a subsequent failure.
Yes, its a pretty big job and prices can vary depending on what all has to be done, but I'd say this job will typically run you around 3k.
The main thing on these vehicle's is to keep the coolant system in optimal run condition. A subpar cooling system (partially clogged radiator, improperly functioning t-stat, improperly functioning fan clutch, or anything else of this sort) results in elevated engine temps which strains the gasket more. The head on this vehicle is aluminum and very long, so you get differential movement between the head and block that typically results in a gasket failure at the #6 cylinder. With all the systems on these vehicles to lower emissions and maximize full economy, you get higher engine temps. Combine that with a poorly maintained coolant system, and that's when you get into trouble.
I try and do a complete coolant flush every 18 months or so.
It's the only major acheilles heel of this vehicle. If it's already been fix, and you keep the cooling system in good order, you've got a highly dependible rig that will last you 300k easy.
Regards,
Rookie.