This is an idea I had since quite a while. Maybe you could add some optional restrictions to the mechlab to make the mechs more unique. What I had in mind is that each chassis can only deviate the engine ranking by +- 10 +-15 etc (could be part of the ship upgrade system too). So for a shadowhawk with 275 default you can only swap to engines in the range of 265 - 285 or 260-290. That way you retain the ability to play around with the speed / weapon tonnage but you can no longer turn an urbie into a javelin.

It would probably make the most sense as a toggle and not mandatory for everyone and maybe as part of the toggle you could re-enable the weapon slot sizes? I don't think I am the only one who on the one hand likes the idea of mechs being more unique but on the other can't resist the temptation to slap much bigger engine for those internal heatsinks and compensate with endo + xl which basically makes all mechs the same.