Not a big deal to build the Fus. first, thats what I'm doing on an RV8-1. The center section comes with the kit, as do the longerones. You must request the longerones at the time of the order! Does not cost much more to ship. They place the longerones in a 2 or 2.5 inch pvc pipe and include it along with the large box that the rest of the parts come in.
There have been some mis-statments made about the center section and wing spars made. Mine for example has two locations with a close tolerance bolt. The contractor who match drills these parts will then send a paper with map of where these larger bolts are to be placed, and mine was wrong. Van's admitted that unless you want to ream all the holes, the center section and spars NEED to be a mathced set. Since I am building the Fus. first, and pointed out this error to them, they have had the contractor who makes these parts make another identical set, and claim to be holding my wing spars. I am going with QB wings, and Van's told me to call well before I need them so they can send my spars to where ever the wings are built.