The best price you'll find on the Thermactor plugs
http://www.store.partsdinosaur.com/product1521.html
Or
5/8-11 x 1" bolt with 2 washers ......2 washers because the holes are slightly deeper than 3/4" before you hit the inside of part of the casting... the washer helps space them out...
Reynaldo rivera
I'd like to help you but that's not my site, you need to Contact Blown88GT here on StangNet he may have what you are looking for.
Here's his info
http://www.stangnet.com/mustang-forums/members/blown88gt.7407/
Look up under the dash toward the heater box above the accelerator pedal and you should see a gold colored vacuum cannister, that is where that vacuum line should attach.