I don't know how streetable a 530 hp 340 would be, but back in the early 80's I had a heavy TRW 12:1 bottom end 340 with home ported W2's an Isky 255/260 @.050 oval track flat tappet with non roller rockers that probably made close to that.

It had a V gate shifter and a hemi 4 speed and 4.56 gears in a gutted 69 Dart, It wasn't hard to drive on the street at all back in the days when we had Sunoco 260 and 280 pump gas.

It gave most of the big block Chevelles and Camaros all they wanted to the point to where within a couple weeks of running it they would scurry away like cockroaches whenever the little Dart pulled in.

You only need about 285 cfm of head flow to hit 500 hp, with fuel injection and good valvetrain I don't think a 530 hp combo would be that difficult to come up with today.