A couple of questions...

[FORDification]

You can use the bracket from any I6 engine, but I don't think you're going to find one that will let you use your present pump. I believe that by the time power steering was available on the I6, the pump had been redesigned. Here's a shot of one I took of a junkyard engine from a mid-'80s truck with a 300:

http://www.fordification.com/board/I6_P ... n-pump.jpg

I would think the van you're getting parts from would also have power steering. If so, you should able to just use the bracket and pump from that.

You could always pull your existing intake and drill/tap a hole for the vacuum hose hookup, but since you'd have to remove it anyway to do this and you've got a manifold already set up for it, I'd say just swap the manifold. You definitely don't want to drill into your present intake without removing it first, since metal shavings from drilling will drop down into the intake and get sucked into the engine...NOT good!

[willowbilly3]

I did have a bracket for the old style pump on a 300 but I think I forgot it in Alaska. I used the newer style pump when I converted my 72 and the only problem I has was the pulleys didn't line up. The solution was to use the pulley puller and pull it back off the shaft about 1/4 inch from bottomed out. (say that 3 times real fast). Just get a pressure hose for a 1980 or so and it should fit the newer pump and still have the right fitting on the gear end.
The manifolds had so many variations over the years that I can't say with certainty, but there should be a 1/4 inch pipe plug you can remove on the side. They did change the bore size on the carb by 79 so your old carb may not fit the 78 intake. I know we were mixing 76 and 79 parts and they didn't match up. I modified the intake to use the older carb and we never could get the thing to pass emissions, or run decent.