Your models do look really nice. I wouldn't be too worried about finding a shader that precisely matches what XXL1 looked like. From my limited understanding I don't think it's possible to recreate this look entirely in UE4, or at least it's not worth the time. Your models are so advanced from the 2003 game graphically, they can stand a bit more realistic shading.
The stone slabs with the painted target on it: There are some small indentations implied in the old textures there, on the corners and edges. Modelling those could help make the thing look more worn-out.
@Herr Epsilon thanks for feedback
The thing is actually I think its possible to mimic a shader of XXL but with modern technologies game will look way better.Since XXL doesn't support anything except diffuse and specular maps.
Also ye I gonna rework the aim target part as well
not bad Rome level 1 in XXL2 style
Bonus randomizer: https://youtu.be/CpRtoTnevyk
It now affects all spawned bonuses, not only from crates, but also from Romans, boars, cages, ..., and can randomize to any existing bonus (helmet, multiplier, food, shield, potion and laurel)
Fast 100% incoming

Or maybe even 200%

With this cheat I can become rich of laurels!