I think most upgrade the rear light due to its position more so than the shape. It is clear it was an add on for the RC and in no way compliments the lines. Besides it just dangling low like it does, there is no rear "square" elements to the RC's design. Tail lamp looks like it is off a 1982 Shadow and put on the RC to meet DOT.
I think your undertail turned out pretty nice. I got a different brand, but im not exactly pleased with fit either.