I would not worry too much right now on the gearbox, l find on my cars they can be a bit “tight” to get into gear (mainly second) when cold, they loosen as they warm up. One thing l find is that snynchro can be a bit weak on 2nd, sometimes 3rd, and l think that some drivers may not push the clutch pedal down to the floor and wear it out sooner than normal so position the seat so that you can really push that pedal down. The clutches are vac assisted and if that is below par then the pedal will be harder to push down, this is not normally an issue just push harder with that left foot just make sure you fully disengage.
I use Royal Purple transmission oil which is 75/90 in gb transfer and diff (gl4 and gl5 compatable) l find this has a really good effect on gears making them easier and smoother to change and when l bought one car, the seller gave me the third gear synchro as it crunched quite badly, now with R P l let the box warm up, miss out third until then and find it fine to go into third, no crunching etc, normal change, not doing a “racing quick shift” ( l think the getrag boxes in our cars are not great for that).
The other thing to consider is the change mechanism itself and make sure the cables are moving freely, you can change bushes and bearings in the system which are not megabucks and if they are well worn will stiffen it up.
Make sure all oil levels are right, goes without saying and check all other service items but the transfer box only holds 0.3 of a litre so not much.
I find a bit of seepage between gb and tr casings is quite common, in an ideal world replace all seals but biggish job, l have used Tiger seal around that joint after a good clean and it works for me.
Anyway thoughts of Jerry hope it helps and have fun with the car, you got it at a good price and should have a bit of leeway if you do need to do jobs, but lets hope not.