I've had 2 of those. Make sure you get a 1600 and not a 2000. The 1600 is an overhead valve engine and overheats warping the head, so it's a good donor. The 2000 is an overhead cam/5 speed like the Z and is too valuable to destroy. Also, the pre 68 has a low, bolt on windshield and the 68 up ha a high body color windshield.
There were some rarly done rotary swaps done in the past, but rotary's & Roadsters are dwindling now. Never seen a turbo done though. I'd love to see someone do it here. I have talked with someone in Canada who sent some pics of swaps up there.
Not only does the Roadster have a full frame, it has a HUGE X connecting the 2 frame rails to each other. It would tolerate 500+ hp easily. No b.s.
I swapped a 2.3 for the old technology turbo mustang/capri back in 80s into a 1967 1600. When it cracked the head, I set a sbc in the engine compartment and it fit right in. The steering shaft would have to be worked over and a remote oil cooler would need to be used. Also, the exhaust runs through the X portion, so an additional hole would have to be sectioned into the X. I wouldn't recommend it for the balance issues, but would be a nice overkill project. The turbo rotary is the better choice.
Doug.