IMHO the 4AGE will net you pretty good power but as far as reliability and availability of parts. It gets complicated...especially for the supercharged cousin.
http://www.radcastro.com/Projects/Pr...T2GT4/899.aspx
You should jump in the Club4Ag boards for more information on the 4A engines. They're very resourceful there.
It doesn't make sense to compare the 3SGTE and the 4AGZE since they are both created for different applications. The 3SGE (non turbo) and the 3SGTE have significant differences and the 3SGTE has specific compression configurations just for the CT26. The 3SGE (rare) is the actual 130-140 HP N/A engine is the one you should be referring to.
In terms of potential...the 3SGTE is a more viable option in terms of power potential and reliability....even for STs
the 3SGTE has appeared in Japan Grand Touring Championships (within a Supra...yes...instead of the 2JZ). The 3S has also appeared in the WRC and Super Taikyu.
My articles:
http://www.radcastro.com/Projects/Pr...4/default.aspx