The Dorman number I found was 675-107. Retail on it is $2.39 here, but Dorman is always high on price. Check local auto supplies if the hardware store doesn't pan out (it should). Chances are if you order it from Summit, you'll have to buy 10 of them. Dorman doesn't sell 'em individually, nor does my warehouse.
The starter cable adapter may work on your car; the spacing on it is different than the spacing on the actual starter. Check it against the cable when you get it. On my 440, the adapter had to be removed because it hit the block. That's not an issue with the small-block engines.
Either of the distributors listed would be OK, I guess. They
are all-new, after all, and Rick Ehrenberg at least has some reputation to uphold. The only difference appears to be the cap, which is either the cheaper black unit or the high-dielectric unvented tan alkyd cap, which is the correct factory color but not vented as original. The vent was a holdover from the points days, where not only was there the high heat of friction from the rubbing block, but the constant sparking of the points created ozone, which is electrically conductive. Venting the ozone helped reduce crossfire. NOS vented tan caps are big bucks last I checked.
I'm not sure which carb adapter you need; it looked like you had several of the steel divider plates that would work to seal the spread-bore intake, including two used ones in
this photo and a brand-new one in
this photo. All it has to do is cover the outer edges of the rear throttle bores enough that a gasket will seal. Being that all three appear to be steel, as long as they're flat you should be fine...
...as long as the front throttle blades clear the intake. I forgot about that bit. Double-check clearance by laying the steel plate on the intake and setting the carb on it as if it were installed. Don't bolt anything down. Now, holding the carb down with one hand, open the throttle all the way. Does the carb try to lift itself off the intake? If so, then you need Mr. Gasket adapter/spacer, part number 1932. Take a good look at it and check with your nearby car pals. There are millions of these lying around used; I think I have several.
Now that starter wiring adaptor I showed earlier came off this starter I bought when I first got the 74, will I need it with the new proper cables?
& finally when I was putting in the up stops, this piece popped off in my hand, could not figure out how & where to put it back, is it important? 
