Judging by the former driveshaft the drivetrain is 6-7" rearward of where it used to be.
If the motor were in the factory location I could push the firewall forward that far, move the seats forward, and the x-brace wouldn't be a problem. However, the weight distribution would bring the suck and I would have less room to lean the radiator back.
I sat in it a few times and moved stuff and the back of the seat now only sticks behind the hoop by 2" or so. I might be able to get away with a slightly bent brace, time will tell.