Getting past the steering rack will be one of the biggest problems. I'm looking at making the car a "front steer" setup, ... which means putting the steering arms in front of the wheel centerline. That means moving the rack forward about 10-20 inches. This requires cutting the front crossmember out of the car and moving it forward. You have to create a hole to set the oil pan down into and have room for the new bell housing. The firewall will have to be cut for the bell housing as well. The stock tunnel is just big enough for a driveshaft, .... but not high enough near the rear to allow susspension travel. So the tunnel would have to be raised/replaced. Now the gas tank is in the way, ... OK, ... a fuel cell behind the rear end, which needs a place to mount and suitable control arms to hold it in place.
The coil springs are in about the right spot, ... but the latteral support bars are NOT!! They need to be moved to behind the rear end. Everything that has to be moved, .... has to have something to mount to. If there is not a "hard point" to bolt to, ... you have to create it!! On a unibody car like this, ... everything is sheetmetal, ... no frame, ... nothing heavy to bolt or weld to. If you tack/ tack /tacktack ... to the thin sheet metal, .. some rear end mounts, ... they WILL pull out!! so you have to make a sub-frame out of steel to mount all this too.
All this welding and cutting of the unibody will weaken and warp it all out of shape! ... Did you build a frame jig to attach the entire car to before you cut it all apart, then started welding all over it??
Scabbing in all these hard points here and there is still not going to make a tight/strong car. Gutt the PT like a cat-fish and roll a complete chassis under ther and then make some body mounts. That's the way to do it! $$$$$$$
Back up front, .... the rack is moved and a subframe fabricated, ... but wait! the steering arms are still behind the axle centerline!!! .. Can we put the right strut on the left and the left one strut on the right?!! ... will the king-pin inclination be correct, ... caster/camber, bump-steer??? will the toe-in stay fairly consistant over bumps? ... How will it handle, now that we have cut and moved everything around??
Damn that heater core!!! ... Did you just cut through it, while chopping the firewall for more bell housing clearence?
Now I got to re-run ALL these friggin brake lines they ran accross the fire wall!! .... $hit, ... they are metric lines and double flaired!!!! where am I going to get line like that?!!
Still want to go this way?!? ... I am still evaluating the things needed to actually get it done, ... but the list of possible dissasters is getting very LONG!
Bob