Headers vs. Manifolds

Wow; you have gotten a lot of GOOD advice here. The good advice is given by a lot of people who are telling you how they would probably do it. Ten different people will think ten different ways. Here is my input.

@Demonracer says you won't miss the horsepower on the street. I agree with that to an extent. If you are strictly driving it on the street and never, ever rev it up or spin the tires, you won't miss the HP. But I think all of us punch it a little here and there and do a quick burnout when nobody is looking. You will miss the HP then. And you have to ask yourself a big question. Why are you putting a big block in a 75 Duster? Unless you are doing it just for looks, the answer is for more power. And if you are doing it for more power, why give up 25-30 HP?

@273 said you could do the logs now and upgrade to good headers later. That is good advice IF the B body logs will fit in an A body, and I am not so sure they will. Evidently, @Carnut68 is not sure if they will fit either. That is why the A body big block logs have different part numbers than B body logs. You need to find out whether they will fit or not before making a decision. Please do not even consider using the fenderwell headers.

If the B body logs fit, I would go that route for now with the intent to upgrade later.
If they will not fit, and the good headers cannot be bought now, wait until they are in the budget.