Do you know of anyone who has some of the older builds? The .687 was the last one I really liked and the 2112 was the last one I had any fun at all playing.
You can find all kinds of old releases here:
https://storage.rcs-rds.ro/links/4729f8d6-f44b-42b7-aa3e-e0ddc6deead6?path=/JA_2/v1.13_Releases/Official/English
You may be also interested in unofficial 2085en modpack, which additionally provides possibility to play with some map mods:
NightOps
Wildfire
JMM
Reconquista
Just select required mod in Ja2.ini and run Ja2.exe
There is also very good Renegade Republic mod available for 2085 (or 2112 exe which is slightly improved version of the same release), though it's not 100% finished or polished but still a lot of fun if you want new quests and such. Renegade Republic is probably one of very few 1.13 mods (together with Arulco Revisited, which is only available starting from 4870 release) which I ever nearly finished.
I also agree that 2085 is one of the best releases for 1.13, it still has a lot from vanilla but at the same time many useful improvements.
To install 2085 modpack, download 2085en + Mods.7z.001 from the link and unpack it into a folder with clean vanilla ja2 game.
https://disk.yandex.ru/d/J3g2YJ7LgCxBgw
If you are interested in Renegade Republic SCI for 2085, you may find it here:
https://disk.yandex.ru/d/uHin4O3wAVY_cw
or here (official 1.13 repository for mods):
https://storage.rcs-rds.ro/links/4729f8d6-f44b-42b7-aa3e-e0ddc6deead6?path=/JA_2/Mods_v1.13/Renegade_Republic