The intake cams are different and the GTE has oil squirters to cool the pistons. The GE would also need to be drilled and tapped for the oil drain and supply. Any used engine I would recommend be fully rebuilt as you've no idea what it's been though.
Personally, I'd pull the current one apart and measure for warpage and get the head vacuum and dye inspected first. If you're looking at having an engine rebuilt anyway you might as well try to save the cost of another core.
