Intake manifold spacers

I have a 2006 300C 5.7 AWD.
Originally bought as a donor car for my '65 Barracuda, but kinda loving the LX platform for now O:)

I am curious if these were intended to use stock 5.7 (pre-Eagle) heads and stock intake and just raise the intake runner height?
There are after market spacers available now, but all I can find are "Adapters" from 5.7 to 6.1 or from pre-Eagle to Eagle heads etc.

If you designed as stock "risers" only, I'd love to try this.
Any chance you have the CAD files still lying around and willing to share with a fellow Mopar nut?

Thanks.