Since your trip is over will bring up a few options to help with keep heat out and moving it out of the cab. Since the heat shield that clamps to the muffler is next to impossible to find (bought my new over thirty years ago when they were still available) would suggest using the 75-78 right behind the skid plate.
View attachment 3535482
Then the 1/75+ that fits under most of the back floor.
View attachment 3535483
It's an interesting option but I guess the 75+ tub must have mounting points under to install them? On my 74 it would mean drilling the body and having nuts inside? (and hopefully not getting in an non accessible cavity)
But for sure the lack of thermal protection here can really be felt...
I installed the vent windows in a 73 hard top more than 40 years ago. Helps a lot with moving air threw and out of the back.
View attachment 3535487
I often wanted to install sliding windows, it sures would help. When not in a too dusty environment I often drive with the hatch partially opened in summer, love the big breeze coming from the back.
Now for ventilation I got it set for this trip, quarter windows in bug catcher mode for low speed, feet doors always opened, and a little USB fan installed to ventilate the back of my head (and when not moving).
Few questions on your 74. Looking at Amayama Trading I see 1/75 as the date for the start 40 series in Europe. Can tell the rear sill is not original. Three footman loops on each barn door ended in 1971. That makes me wonder about the front bench seat. Thought that style ended 9/72?
Not sure where you see that? On the European EPC the FJ40 is listed from 1969:
Electronic parts catalog for Land Cruiser FJ40LV- complectation. Engine, chassis, body and and electric spare parts for FJ40LV- Land Cruiser.
toyota-europe.epc-data.com
In France 1974 is the first year of import but some other countries got them a good bit earlier. Noticeably Switzerland started imported a few Land Cruisers as soon as 1968 with the famous FJ55 of baron de Rothschild:
Toyota FJ55 Une voiture de maitre - Pièce occasion - Casse 4x4 - https://www.modulauto.com/toyota-fj55-voiture-maitre
Yes on mine the rear sill was re-done and the barn doors had to be changed... The one I sourced in the US had the 3 loops and I let them but yes my original only have 2. In France we kept the barn doors on the 40 until the end but the hinge are different on barn doors from 1976+ and you can't mix... so very hard to find a correct one here.
For the bench seat it's the factory configuration of mine, title is 3-seater and seat mounting points are different from the 2 seaters version on the tub.
Original owner had the original seats replaced by Bostrom suspension seat. The original passenger bench seat was installed in the back where a jump seat would go. When my father bought it he also got the original driver seat with it... when doing the restoration he was positive he had kept it in one of the basements of the house... let me say that I returned every square inch of those basements searching for it and it had disappeared

I now have installed a 1973 driver seat (and I also found a 1975-1978 driver seat) but I am missing the very very rare 09/73-07/74 only driver seat for 3-seater configuration with both a tall back and a wide seat...
Seats are a long story
The complete story here:
Front bench or not? - https://forum.ih8mud.com/threads/front-bench-or-not.1208426/
Curious how the exhaust under the skid plate survived your trip? Around 1990 I bought the OEM header pipe, muffler, tailpipe and muffler for my 68 while they were still available. Removed it shortly after installing. Put a dent in the leading edge where it went under the skid plate. A lot more rock than sand in Northern Arizona. Sure it's still in my pile of exhaust parts. The above the skid plate routing started melting the PTO case. So pulled the PTO winch. Probably go back to stock on that cruiser or on my 73 FST.
Changing the exhaust is the very last thing I did before leaving for Morocco. The tailpipe was full of holes because the exhaust had moved a little and it was oriented in a way it was collecting water...
But Silencer and center pipe were still good.
Changed all of them for an OEM silencer + reproduction pipes sold by Euro4x4parts (kept my original parts in storage).
The new OEM silencers took 40 days to come (so probably coming from far) and came in absolutely no packaging and full of logistic stickers on it, only the Toyota PN sticker was easy to remove... Also welds in the part where you insert the pipes were not cleaned flat and I had to do it to be able to fit the pipes....................... complete PITA
(checked on my factory one and all inside welds are perfectly cleaned flat)
But for your question, no I did not get any issue with exhaust in my Morocco trip... It never touched and did not went over big rock (and did not got bogged in sand).
My old center pipe touched a few time on offroad situations in Europe but never got damaged by that.