2006 4.8 non-flex

I removed the stock injectors and installed some Siemens deka 60s. From my research I know that 1/2" spacers and longer bolts are required so I purchased them prior to install. My problem is I don't think 1/2" spacers are enough, 3/4" might work though.
Has anyone else had this issue? I'm pretty confident the injectors are all the way down.

 

I thought they required 5/8

 

Initially I got the info from Sloppy Mechanics. All of the other "how to" pages and even kits I found use 1/2" fuel rail spacers. I'm unsure

 

When I put my 80 lb injectors in a used some brake line and longer bolts and cut it to roughly 5/8 like mentioned

 

I cut mine to about .6 and it was a tad short. .75 probably would've been spot on.