i'm considering reducing my 750grams rice to 600 grams rice and adding the difference in olive oil (70grams?)
so that i have to eat less
would this negatively affect my lean gains?
I don't think that it is possible to make that determination. You'll have to experiment and see. For me, I am pretty carb-sensitive and would probably do well on fewer carb calories and more fat calories (sorry, TA).
IIRC, you do well on more carbs, so YMMV.