The LV-909 is hardly there either. For those who wants the quick run down of the charts: Vacuum For stages with target TWR ratio below 1 use multiples of the LV-N (atomic engine) or multiples of the 48-7S if you wish to lower the weight of the stage. For very heavy payloads use only 48-7S's For stages with target TWR ratio above 1 use multiples of the 48-7S Atmospheric Use multiples of the 48-7S, unless your target TWR is less than 1.8 - in that case you can use aerospikes if you have a very heavy payload with high DeltaV requirements (IE heavy stuff with lots of fuel in the stage). TL;DR: Use multiples of 48-7S and attach the engines in symmetry by using the tiny "Cubic Octagonal Strut" as adapter. It will attach pretty much anywhere on most parts.
