I'm going against the grain here and saying "it depends." BE REASONABLE and you can sell much of it.
Intake and carb - these have value. Carb is non computer control, and guys with malfunctioning computers or removing emissions like this. Price it as a core because anyone who buys will want to add a kit and rebuild. Intake has value, but less of it. Not every 2bbl 231 intake was created the same. In later years they used an efe heater element between the carb and intake. Some intakes were notched for a recessed version of the efe heater plate (which over time could melt/fail.) A VERY limited market would pay a couple bucks to replace their intake with yours, but, lower desirability.
Exhaust manifolds - not worth much more than scrap. Wouldn't have the O2 sensor molded in, but, most people would put something better than the cast iron on. You could get a few bucks, but if imagine not alot.
Engine accessories - not worth much. Take what you can get but be cheap. Not worth much more than core value.
Engine brackets - usable on a buick 350, lack of an air injection reactor (a.i.r.) system pump mounting points helps clean up the appearance, but, sounds like you're reusing those anyways.
Anything else? Again, not worth much. You can get stronger 2 dot cast rods from a turbo motor for around $10 each. So, not much incentive for yours if you're removing.
Not sure what else you think may have value, but, if say $50 on carb, $20 intake, $10 exh manifolds, and core value on engine accessories covers most of your values, at least in my opinion.
