Hey guys, i am currently learning more about river betsize with combinatorics.

My question is if we are in a spot where we have 60 value combos and 40 bluff combos on the river we should size it up to 60% river betsize to play GTO?

And if so we are playing a weaker calling station. How should we exploit that?
1. cutting down (or remove all) bluffs?
2. sizing up bluffs? (or sizing down?!?)
3. Betting bigger for value aswell?

Any rule of thumbs?

Cheers

If you want to see if the numbers add up, you have to do the math.

In your example, you bet 60 in a 100 pot on the river, so your opponent has to call 60 into 160. Does that add up with him being good 40% of the time?

If your river range if 60/40 value bets/ bluffs and value is 100% equity with bluff equity= 0%, then you should bet twice the pot to make villain indifferent between calling and folding and therefore he cannot exploit you.

Villain EVcall = -0.6*2 + 0.4*3 = 0

The minimum defense frequency (MDF) rule is to call such that bettor does not profit from a pure bluff. MDF = Pot/(Pot+Bet)= 1/3. So, if you follow that (and it is not a universally accepted rule), if one calls greater than that, to exploit, you as bettor should bluff less and if one calls less than that, you should bluff more.

Assuming nuts or air is somewhat unrealistic. If your value equity is, say, 85%, and your bluff equity is 10%, say, you can show the bet should be 4.5Pot.

Villain EVcall=0.6*(-0.85*4.5+0.15*5.5) + 0.4*(-0.10*4.5+0.90*5.5)= 0

Playing GTO isn't as simple as dividing your range into value hands and bluffs, partly because villain doesn't always have a pure bluffcatcher. (He can have some strong hands that actually beat some of your 'value hands', so it's rare that 60% of your range always wins when called and 40% always loses). All that said, if you wanted to bet in a 60:40 ratio, the size should be 2x pot, as statman said.
Just remember that a "balanced" range for a pot-sized bet would mean you have air a third of the time (a 2:1 value:bluff ratio). If you want to bluff more than a third of the time, you need to go bigger than pot, essentially to give the bluffs a better chance at working.
It obviously depends on his specific tendencies, and how he reacts to different sizes etc, but generally speaking you should reduce your bluffing frequency (sometimes down to zero), but increase your sizing with your value hands, until you reach a sweet spot where your bet size multiplied by the frequency it gets calls maximises EV. e.g. Getting a $100 bet called 50% of the time is more profitable than getting a $50 bet called 90% of the time.
Exploitatively against fish that aren't particularly cognisant of betsizes (e.g. they've decided to call or fold whether you bet half pot or 3/4 pot) you can often get away with going big for value, but a bit smaller with bluffs.