I think it would be helpful to be more specific about what you're trying to determine.
For instance, "what percentage of income should go to the government (assuming a social context where that even makes sense)" is, from a consequentialist perspective, a question that ought be decomposed. Any given program might or might not produce additional value over the marginal cost of raising the money for it, depending on the details. So maybe you want to ask questions like "what is the marginal elasticity of labor [at various incomes and social contexts]" and "what is the marginal effect of income on [happiness or whatever you care about] [at various incomes and social contexts, blah blah blah]" so that you're better-equipped to make cost-benefit analyses of various programs, and so on. As it happens those questions are of course totally politicized, but it's better to know that they're the actual questions you're looking for (if they are.)
You might be asking something quite different from this, but if you are, it should be decomposable, or at least made more precise, as well.
[see 'Update' below]
I know discussions of actual applied politics are to be avoided. I don't want to start one.
But I thought LessWrong people might be a source for where the best arguments have been made for libertarianism in the economic sense (not why you should stay out of people's bedrooms). Even better, arguments for some degree of socialism in the same place would be nice. It seems there is a natural continuum. To pick one specific realm: anywhere from 0% to 100% of a person's income could be allocated for redistribution to even things out. Where to put that number will inevitably be a matter of grubby politics (won't it?). But still, arguments for why we should have a low number or a high number must involve some basic disagreements which could be (hopefully) separated into different values, different estimated probabilities, and different attempts to apply a rational analysis.
The world is dripping with partisan analyses along these lines (with "warfare" rules). Where are the best ones that avoid that failing?
I considered posting this under "dumb questions" but I judged that it's not really a question about LessWrong per se.
Update: Thank you to all who took the time to reply. Perhaps I'm learning about how some would start applying consequentialism to a real-life problem. I expected people to point me to discussions about what's right and what's fair -- which is what I'd expect in most other forums. But I guess here my responders so far are taking this to be a sort of question for technocrats who can work out the utility. So my next question will be about consequentialism once I've thought about it a little more.