If you're not so familiar with the RB26DETT, it is the engine that Nissan put in the previous three Skyline GT-Rs- the R32, R33, and R34. (The current new GT-R has a V6). It is also a very popular 'drop in' for some other Nissans, like older Fairlady Zs.
Tamiya included a usable RB26 in their first R32 kit, but their R33 and R34 kits have been curbsides. Gio has designed this one so it should work great in both street or racing Skylines.