73 Chevy v8 question

[Stowe, Ted-SEA]

Thanks very much to everyone for helping me id my Chevy 350.

I believe it to be a '73 350 out of a passenger car, which one I can't tell,
I am assuming a 2 bolt main. whether it was rebuilt or not I can't tell.

the head casting # is 3973487
the carb id, (2bl Rochester ) is 7043114
the block id is 3970010
the intake is 3997773

the distributor I can't find listed anywhere, it is a 1111440  8c19, the
8c19 would normally tell me that the distributor was built on march 19th
1978, but how that got there I can't tell. It is a single point dist.

I cannot get the waterpump nor the exhaust manifold numbers.

a great numbers book is 'Chevrolet by the numbers' really nice for this sort
of thing.

I have a question about the intake manifold, this is not a efi question, I
wish it was but I am trying to do the right thing here. Putting an efi
system on my mgb has taught me to pay lots attention to details and think
before doing anything.

I took the carb off and sent it out to be rebuilt, as it idled funny +,-
300+ rpm, and I took the intake manifold off and had it tanked because it
was just too dirty.

I did this also because the egr valve appeared not to work, and after seeing
the egr valve passages from the outside all clogged, I just thought that was
the problem.

now with a clean manifold I think I see something else. this 'egr' manifold,
has two small ports on the passenger side, that would appear to mate with 2
ports on the head on that side. these ports are right under the egr valve on
that side.

however there are no ports on either head for such a purpose, and no holes
in the old intake manifold gaskets either. so even with the intake's egr
ports cleaned up, nothing is going to happen. 

so is this a clear case of a different set of heads/manifold ? or is this
not a problem ?
does anyone sell an egr valve block off plate ? I'd hate to kind of leave
this condition existing as the egr passages are just going to load up with
carbon again.

also, in looking at the HP ratings for 350's around that time, (73), what
happened to the HP ratings ? this engine would appear to have a hp rating of
145. the 350's prior seemed to have about 25+ more, was this a different
method of measuring hp ? or was this the result of the emission requirements
at the time ??

I accidentally got a set of felpro intake manifold gaskets that appear to be
for a intake manifold that blocks off the exhaust crossover. I would guess
that this was done to help cold running conditions, any advice on retaining
this or not ? 

thanks for all you're help. when finances and time permits I would just love
to efi this.
this is a 350 in a 72 xj6 with a turbo 350, I plan to put a 4 speed auto in
it sometime.

Ted Stowe