As the tuners figure the new motor out more it may be attractive to drop one into a FD chassis. See (Turbo RENESIS). Mazda USA has also been working on a Supercharged RENESIS though the results have been less impressive performance wise (though they've done some very nice suspension work it sounds like as their ~275hp RX-8 was running better lap times at Willow Springs than Boxsters).

Questions to be answered (at least for me):

1. Does it fit?
1a. On the existing subframe?
1b. On a new subframe?
2. Does the FD 5 speed mount up to it?
3. Does the RX-8 6 speed fit under the FD?
3a. In the existing location?
3b. With new holes through the floor?
3c. With new supports welded on?
3d. On the existing drive shaft?
4. How much does the RENESIS motor and needed accessories cost?
4a. What FD accessories can be used?
4b. What new accessories much be purchased?

 

https://www.rx7club.com/showthread.p...sis+conversion

https://www.rx7club.com/showthread.p...sis+conversion

 

So it sounds like...

1. Yes
1a. No
1b. Yes
2. Not clear, probably no, not your best bet.
3. Yes
3a. No
3b. Yes
3c. Yes
3d. No, and you probably want to use the RX-8 rear end as well.
4. ???
4a. Pending ECU you may have to swap in all of the RX-8 components, ABS, gauges, everything.
4b. Depends on what you do for ECU.

Basically it is at least if not more difficult than swapping in a V8 so until we start seeing 400+ numbers out of the RENESIS it probably won't be worth it but the current turbo is a step in the right direction.