my two cents too
although it does not reap HUGE benefits, i believe that freeing up the motor by removing some of the loads on it has a greater effect on smaller motors,
first thing to remove would be mechanical fan to be replaced by thermo but also freeing up flow with use of beter exhaust, GX head and as stated before better carburation and as you get more serious elec fuel and water pumps ect. (water pumps are expensive but try 4x4 wreckers for fuel pumps, i got two off a L28 patrol for only $40

, good pumps too though old)
i actually helped my mate put a 32/36 on his 1600 gemini and it made a great diffrence as the car lit up at high revs as the bigger carb was feeding it much better, people said without other mods to the motor the carb swap wouldnt make a diffrence but it sure did up high in the revs, though it leaves us wanting to improve the bottom end aswell so dont forget that (thermo fan will probably help a bit here), then theres the handling of a gemini but i wont go into that