Without the split ribs (I - Beam) it would just be another smooth flying airplane,
Oh, I dunno, Bob. If construction is equal to or lighter in weight and the same airfoil profile is maintained to not affect aerodynamic performance, I imagine it would still fly the same. At any rate, the plan is available so one could reproduce the Lancer with split ribs and I-beam spar in all its former glory.
The Interceptor was a cheap copy
Interceptor doesn't appear to be a cheap copy of the Lancer. It seems to follow the proportions of the old S-1 Ringmaster with regard to area and similar thinner rib section, except wing appears to have a slight leading edge taper. In the instructions, what appears to be split ribs in the isometric drawing are simply the root wing ribs, which provides the foundational support for the rest of the wing. Rest of the ribs are standard 1/16" sheet. Wing root construction to fuselage is odd, in that the Interceptor's fuselage's penetration is only for the part from leading edge to spar. Split root ribs are butt joined to the fuselage sides, to support the back side of the wing.
In my remake of the Interceptor, I plan to make the fuselage as per standard practice of the times and as of today. That is to have the wing constructed in whole, to slide through a fuselage cutout the size of the wing profile at its center. This will also ensure a wing without warps. The Berkeley way was to construct the wing together with the fuselage, which makes things unnecessarily complicated.
Also dispense with the solid 3/8" thick red oak fuselage front. That bugger is heavy and unnecessary for flight. I plan on using standard hardwood engine beams and plywood planking on both sides of the front.