RB20 to S13 Wiring Question

[s14Geoff]

Hey guys just had a quick question about the wiring. From reading a few guides it seems like all i need to do is swap some connectors and solder a few wires. My RB harness came with the fuse box also. Do I swap the 240 and RB fuse boxes? Or do I cut off the RB box somehow? This is my first swap so bear with me... and also for the wires and connectors i don't need what would i do with those? Just leaving them hanging around seems like it would make my engine bay look like a rats nest.Trying to save $500 by doing the wiring myself. Uploaded a picture if it helps any thanks guys. (sorry for the huge paragraph)