I finally plugged the manifold ports because I'm
installing it tomorrow.
The best I could find to plug the emissions holes
were tractor wheel lug bolts at Tractor Supply.
They were too long so I cut them shorter.
The threads were a hair off. After 3/8" of
screwing in they would start to cross thread.
I cut them to 1/2" long and tightened them in until
they bottomed out agains the tapered head.
I used high temp threadlock also and they are
very tight and seated well.
The farthest hole to the back was different.
My old manifold has this one emissions port
which is jury-rigged plugged.
I found that a standard cast iron pipe plug
fit this very coarse thread perfectly and
I installed it into the new manifold as above.
I don't know how they'll ever come out,
but with my luck they will.
Thanks again for all the great advice. I still
can't believe I found a brand new manifold
using the recommended links.