Minecraft – the best layer to mine for gold in Minecraft

Routers are, in my experience, your best bet here, you can configure one router to pull the scrap out (set the router to extract from a side), and one router to insert the required items (insert into top).

This way you need one Export/Level emitter per type, up to a maximum of 4 per router (technically you can add more per router, but it's messy). If you want more than 4 types of items you can add another router set to insert at top without problems.

This setup would also be easier to expand as you would just need to run IC2 power further and add the block next to the existing system. (http://imgur.com/a/wdnDY)

Use water to push them into a shaft that's(I believe 24 blocks?) deep so they have half a heart left, use a half slab so they can't get out but you can still hit them. Due to MC spawning mechanics, it would only help you if you put the second spawner 16+ blocks away.