Point weights for 70-90m

I am trying to fine tune for 70 and 90 m and get the highest sight marks .

I use 40# limbs ( wiawis one or KG nexgen) at 29.75" amo draw on 25" riser.

Arrows are VAP 500 or 600 spine tuned by length and point weight bareshaft at 40-70m to fall in centre of fletched groups.

All fine so far BUT then I look at the effect of point weight on arrow speed and grouping and sight marks at 70-90m and am unsure of the best way to go ( I don't have the money to keep buying sets of arrows cutting points to weight and altering shaft length to get the best for my bow at these longer distances)

So I am seeking the experience of forum members ...

Should I go for lower point weights = higher fps ( more drift and softer spine) or higher point weights = lower fps but more inertia and momentum?

I use 140 gr points at present but dropping this by 20 gr had improved the sight mark at 70m .

I know there is no perfect answer just interested to learn of other archers experiences :)