Had considered the aluminium spacer, BUT...
I havent got much more room then some of you guys here! It a 1974 ford cortina, and our main issues with these is brake booster clearance. I've already used a bracket from a later model corty, but as you can see from the pics below, the choke on the holley gets pretty close to the master cylinder.
Its not certain if i'm ever going to get an aluminium head. They are way expensive, and by the time i go through the complete process, I could build a pretty warm crossflow for what i'd have to spend here.
The main reason i'm looking at the 4v intake right now is so as i can get a holley 465 or 600 (depending which cam i choose) to fit under the bonnet. I dont want to mill an orig manifold because they are so rare, and to use a spacer plate would raise the carb too much. I've already raised the bonnet to fit the 500 under it. But the 4bbl carb would sit higher then the 500 because the spacer i have is nearly 1/2 inch bigger. Then, again its trying to flow through the original 2bbl ports on the intake plenum
Here's a pic of how i raised the rear of the bonnet to clear the 500. The front closes fine, bu the rear is about 1/2 inch higher. It actually works quite well, because there is a mass of cool air trapped between bonnet/windscreen when travelling which now gets forced under a bonnet, similar to a reverse scoop setup.