Why wont it start?

[corn]

I took a 350 out of my 69 & put the 396 back in & now it wont start. It wont click or anything. Good lights & everything else, Im sure Im just overlooking something easy. I have it converted to an internal reg alternator & have an HEI in it . The HEI was done when the old engine was in it so I dont think its that but not positive. I have the purple wire on the starter solonoid towards the engine(inside post) & everything looks to be hooked up. Any thing you can think of that I may be overlooking? I also thought maybe the brushes were stuck in the starter from it sitting but it doesnt click or anything. The headlites dim just a little when I turn the key to the crank position too. Im feeling really stupid here...