[Henry Schmidt]

Two thoughts:
3 inch runner extension will offer little or no noticeable change in performance.
When Chrysler (under the design leadership of David Long) experimented with extended intakes runner back in the 50s, the data showed a need for runner extensions of 32 inches or more to effect real change. Even VarioRam intake have almost three feet of runner change.
If you insist on running spacers, you might find putting the spacers between the head and manifold will make the linkage easier to manage.
Just my 2 cents. Cheers

BTW: nice work so far, your project looks great.