The SVO manifolds are made for the aluminum SVO heads. None are made to use/"work" with iron 4v Ford heads.
You can epoxy anything up to match anything but that doesn't mean it's a good idea.
The A331 is made for the A3 heads. It is essentially an Edelbrock Torker made to match those heads.
The top of the port is raised about 1/4". The bottom raised about 5/8".
In order to use it with the iron heads you really need to use a spacer plate to block the bottom on the head port to match it.
Why not just use an Edelbrock Torker?
The B351 spider intake is made to use on the Ford Motorsport B351 aluminum heads. You can use it on the A3 heads also but you don't touch the port matches at all. You leave them alone.
To use them on iron 4v heads you will have the same issues as the A331.
The bottom line is there is very little point in using the SVO intakes with iron heads. These were components of designed systems intended to match each other. You match the intake to the heads. And yes, I have run the various Ford aluminum head combinations.
The iron 4v heads have a different valve pocket then the "Ford aluminum" heads do. They may look the same but they are not. The iron 4v heads just become obsolete with them. Don't bother.
The risk of using epoxy on the intake side of an induction system may be deemed "an acceptable risk" on something that gets torn down a lot like a '70s period "Pro Stock" engine but on a street engine is just a disaster waiting to happen.