I usually just lurk here at the moment, but since your project car is one I'm particularly fond of and familiar with I thought I would chime in...
Regarding your thoughts around one motor per wheel - I think the effects of this won't be as severe as you're thinking. Obviously it depends on your controller arrangement as to what the behaviour is, but it shouldn't effect handling when coasting or totally off the power as there is nothing forcing the motors to turn at the same speed (unlike a locked diff where both wheels are always at the same speed). Probably the main time it would affect the behaviour significantly would be powering out of corners, but I think you may be able to overcome any unwanted behaviour there with changes to suspension setup and wheel alignment.
A slightly out of the box idea would be to consider mounting the motor in the fuel tank tunnel, with a driveshaft running through to a standard RWD differential (from an IRS rear end, not live axle). This would allow you to get a decent gear reduction (I guess if you search hard enough you may find a suitable diff with a ratio of 5:1? I think I remember hearing there were some quite short diff ratios available for the Toyota GT86), and it would also leave a lot of the engine bay free for batteries. That would keep the bulk of the new weight in about the same location as the original layout, and you could move the motor fore or aft as needed to help achieve the target weight distribution. Obviously this option depends on the motor being physically able to fit into the tunnel, and I haven’t seen many of the popular EV motors in the flesh to have an idea of the physical size of them.
Regarding your thoughts around one motor per wheel - I think the effects of this won't be as severe as you're thinking. Obviously it depends on your controller arrangement as to what the behaviour is, but it shouldn't effect handling when coasting or totally off the power as there is nothing forcing the motors to turn at the same speed (unlike a locked diff where both wheels are always at the same speed). Probably the main time it would affect the behaviour significantly would be powering out of corners, but I think you may be able to overcome any unwanted behaviour there with changes to suspension setup and wheel alignment.
A slightly out of the box idea would be to consider mounting the motor in the fuel tank tunnel, with a driveshaft running through to a standard RWD differential (from an IRS rear end, not live axle). This would allow you to get a decent gear reduction (I guess if you search hard enough you may find a suitable diff with a ratio of 5:1? I think I remember hearing there were some quite short diff ratios available for the Toyota GT86), and it would also leave a lot of the engine bay free for batteries. That would keep the bulk of the new weight in about the same location as the original layout, and you could move the motor fore or aft as needed to help achieve the target weight distribution. Obviously this option depends on the motor being physically able to fit into the tunnel, and I haven’t seen many of the popular EV motors in the flesh to have an idea of the physical size of them.
