Don't bother with a GZE bottom end. They are lower compression than a 4age and a bit heavier to handle boost. You want higher compression and a lighter internals for better RPM and top end in a NA engine. What you want to find is a 7 rib bottom end (ie a 100Kw). Adding the 20v head is a nice idea but a 4age 16v 100Kw with nicely setup 40mm Webbers, Del'Ortoes or Solex's would do the job fine. If you do go carb learn how to tune them as they do fall out of tune every few months or so.