Some of the main differences:
GE has top feed fuel injectors/rail, GTE has side feed
GE has a 6 stud exhaust flange, GTE has 7 stud, later ones had 8 (or was it 9?)
Reportedly the 3S-GE has about 0.3mm more lift on both cams, and slightly more duration than the 3S-GTE
The 3S-GE uses a tensioner arrangement with a simple spring, whereas the 3S-GTE uses a hydraulic tensioner. The parts will not swap as the 3S-GE doesn't have the bosses in the casting for the hydraulic tensioner to bolt to
Anyway, I've taken some pictures of the ports for the sake of comparison.
Exhaust side. First is 3S-GE, I put the 3S-GTE exhaust gasket on to make comparison easier:
and the 3S-GTE:
Inlet side, 3S-GE first. For some reason this already had a T-VIS gasket on it, so you can clearly see the difference in the port size:
and the 3S-GTE T-VIS head:
And stolen from Richard Doig's website, here's a Gen 3 inlet side:
Close up of the inlet ports, 3S-GE first. You can see this is a fairly uniform size right the way down:
And the 3S-GTE one, this tapers quite severely from the large size required by the T-VIS system, down to roughly the same size as the GE head:
And finally, here's a shot of the combustion chambers. The valves appear to be the same size, but I'll measure them later. 3S-GE first:
Notice how the 3S-GTE is much whiter on the exhaust valves? I'm guessing this is due to the extra heat created by the turbo engine.
In conclusion, there are some matters of slight concern for using the 3S-GE head in turbocharged applications; namely the low number of exhaust manifold studs, that could lead to warping of the manifold; the use of a spring loaded cambelt tensioner rather than a hydraulic one; and finally the need to make a custom inlet manifold.
I believe the head will still flow close to the same amount as the 3S-GTE head, as about 2 inches into the port they're both about the same size, and the uniformity in cross section of the 3S-GE head should reduce energy loss and improve low rpm response.
I will not be using the 3S-GE head on the SW11 at present, as I want to get the car running, not stuff about trying to find some top feed 440cc injectors and making a custom inlet manifold. It may be on the cards further down the track.