The problem:
Using these headers:

and this manifold:

Come up with a system to bolt both
to an "A" block. Here's one solution
(used on a Pietenpol):

On the Piet, the "angles" (made of 4130 steel)
do not hold the exhaust pipes -- they hold only
the cast iron intake manifold to the block.

So it would be better to use studs, like this:

Then we heard from the expert, Dan Price, who said:

Using angle iron to make those things never turned out to be very strong.
What I did was take a piece of 7/8 inch round stock and drilled a 7/16 hole in it, then milled away half of it except the last 1/8 inch -- I let that part of it serve as a washer.
Usually the manifold's 'ear' thickness is about 3/4 inch, so you need a piece of stock 7/8 inch diameter by 7/8 long to make these things -- and they're really strong too.
I can see the angle iron pieces collapsing when tightened down a lot. That's my two cents worth for the day."

Here's Palmer Lawson's solution.