The L28E would have better low-down torque, so better off the line. I vaguely remember that there wasn't a great deal of difference in power output between the L28E and L20ET, in stock form. Of course the advantage of the turbo is that it is easily boosted.....
The vast majority of L28E's were saw in Oz are pretty asthmatic, but there were a few 'higher spec' engines brought in by engine importers and mainly found their way into 240Z/260Z, plus some early Skylines, etc.
Just keep the L28 and turbo it