Even the LS motors are "old skool" in this day and age, you boys need to start looking at the direct inject GM engines (motor are electric) hell even the ecotec is a huge step up from an LS if you wanna talk power to weight. 2.8l Cummins isn't out and won't be for a while, there are several other diesel options out there too in the last 3 years or so. All of your options are archaic if you ask me?
personally i love the power and economy of the ford units, and they have factory stand alone ECU's available, its just typical ford that the bell housing change with the blowing wind. try making one work.
to that end, the LS is new 350. its a tidy package that will have aftermarket support until gas engines are no more. fuel efficiency is great, the variety of displacement and materials is unrivaled, as is the durability. i already have the adapter parts, i just cant make up my mind if a complete rebuild is worth it, if 120k dropouts are 500 bucks local.
i like the feel of a big 6, but the 2f is piece of ****. its based on 1930's chevy design with 4 main bearings. a 700 pound motor that cant rev and only produces 135hp will last a long time. it takes power to break things. on that note, if i could swap a 300cid ford as easily as an LS, it meets the minimum performance threshold so id likely waste my money and do it.