Where to buy a good motor plate, oil pan, headers and Valley Tray?
Car has a stock front end.

u no were my house lol

headers have to be custom built i built a set for a r3 w9 headed demon with a stock front end last year they were three steps 30 inches long 17/8 to 2 to 21/8 werent terrible but werent the easiest to build either

As mentioned, headers must be custom. I just finished converting mine to coil over to make that situation easier.

Oil pan is stock, motor plate is the same as a standard block (unless it's a low deck).

Ritter makes a really nice valley tray, here's the only pic I have on my computer here at work. RyanJ got mine for me...

Not exactly the same deal , but I got a header kit in un welded form from Stahl and W-9 flanges from SPD ( www.spdexhaust.com )
It is going in a 1965 Dart , but I am switching to an AlterKtion up front so I can use the later A body headers.
I went with a 1 7/8 primary and for what I plan with it , this should be fine .... but you could step up to larger diameter.
This was the most cost effective and least labor intensive of all the options I looked into.
I should have less than a grand into them after coating.
And the price of having a set cobbled together was downright scary.........but not as scary as the thought of trying to build another set of headers.
I did a set for a 429 Ford in a '66 Cyclone way back when and though the physical scars faded years ago , the emotional ones linger on.
I went with a Stef's pan , but haven't received it yet , so I cannot speak to the quality or fit.
But it lists an integral tray and comes with the pick up for around 3 bones.
I am waiting for the valley cover from Ryan too.
He seems to have the best ideas of where to dig up parts for these things of anyone I have talked to.

While we're on the subject........ does anyone make a water manifold that plumbs the heads to the radiator ?
I have a couple ideas , but nothing set in stone yet.
I am planning on #6 on each end and #8 in the center.........ideally going into a log type manifold and #12 from each side to a filler neck type of deal with the temp pick up here and 1 1/2 " out to the radiator.
I don't like the idea of six lines all running forward........mostly from an aesthetics standpoint , but it would also kind of suck trying to figure out , route and finish that many AN hose / fittings.

There is such a thing as a W7/8/9 water manifold, but I've only ever seen one in my entire life. And it was CRUDE...

How about using hard lines? I think it would look cleaner then the AN stuff...

I'll put my best people on it.
I have a couple friends who are top notch machinists and we'll see what we can come up with.
I also think hard lines , but I am envisioning them from the heads to a manifold , and from the manifold to a filler neck , then to the radiator.
I have the AN fittings for the heads , and I think that flared tubes to these and the other ends welded into a manifold might be what I want to try.