I ended up picking the raasks as they're the only bolt on rearsets for the '77-'78 bikes. I had tossed around the idea of fabbing up some custom ones and welding mounts onto the frame, as well as using rearsets that mounted using frame clamps. I've been a bit time constrained (work and such), so I just opted to cut my losses and keep things moving along by going with the raasks.
That said, they are pretty much bolt on, but as others have mentioned they're not super awesome.
And yes, the top engine mount bolt had to be flipped around (so the head of the bolt is by the rear brake light switch), and the other end threads into the bracked on the shifter side.