If you have access to a SOHC ZC for cheap, build that block and forget about your D15. You'll get more displacement with the SOHC ZC (1.6L) and have a stronger block and more aftermarket support.
The LS rods will only work in the D16 (or SOHC ZC), but aren't necessary (or desirable, too heavy) for an NA D build.
Run the SOHC ZC bottom end, DOHC ZC pistons (PM7 or P29), a Z6 (12.0:1 comp) or Y8 (12.6:1 comp) head, Y8 manifold and a nice cam like the Crower Stage 3 plus matching valvetrain. You could be done for $1000 in parts if you shop around a bit.
That combo can easily put out 160whp if you tune it well, and it would all be built from OEM parts except for the cam and valvetrain.