Fira does have the one combo of straight flush here... Should that prohibit me from making this bluff?

seems alright, though if we use this sizing on river we can't thin value stuff like 2pairs sets straights since IP will usually not call worse

I'm not sure I follow. For non-river spots I attempt to have my sizing based on the board and what position I'm in, but for river I value bet different hands with different sizing, and balance them differently. With most of the rest of my non-nutted value hands I'm betting (which I think on this board would be 2-pair+) I will probably make a more normal size like 2/3s on river.

oh i see... i just use one sizing for pretty much all spots, river and non-river. so i devise a sizing that fits my range, usually an amount i want to bet with my most common/average value hands. reason is i don't like to have capped ranges, which can happen if i'm using different sizings depending on my hand.

Its better to have multiple sizings; as long as u balance it u won't be capping yourself.

HgoD will not always shove river for value with the nut flush; he will shove it an appropriate amount to balance this bluff (he isn't taking this line with any AcXx 100% of the time) and then he will also bet it 2/3rds at a lower frequency so as to not be completely capped.

From what I have seen looking at solvers you want to have at least some of your 'nut' hands in each of your river sizings.

yeah that's what i figured it would take to balance. i don't do multiple sizings though because i would not know which of my AcXx hands i'm bluffing this way, and i wouldn't know which of my nut flush hands to bet 2/3 with. so i just have 1 sizing for simplicity sake. maybe i'll consider doing diff sizings but atm i just have zero clue how to balance. one idea is use a random number generator to decide... hmm lol

I just click buttons randomly: also a way to decide.