Thanks, guys.
It's going in a 510 to clear the rear-sump Buick 215. I do have the early 240 rack. If I use the S30 X-member, I lose critical space for the exhaust to run between the x-member and starter on the passenger side. There is X-member structure behind the arm on the S30, whereas the 510 has the arm behind the member, in single shear. Also, I'd need to recess the sheetmetal and move or duplicate the formed doubler plate that's on the outside of the chassis, since the 510 needs an extra pair of holes to put the S30 piece in the right spot. The doubler plates provide extra space for the X-member bolt heads. I keep thinking that I'm going to end up wanting to convert this car back to stock sheetmetal when I'm too old to work and it's the only thing of value I have left, so the fewer sheetmetal mods the better.
The whole thing is a mess and I wouldn't go this route if I had it to do over again, but here I am, with a valuable engine that should do what I'm hoping for (torquey, with linear throttle response).
Cary, guess I'm most curious about relocating the LCA inner pivots out and up (how much?) This should act similarly to bumpsteer spacers, but I wonder if those original locations are always off, compared to rack width, or if it's only a problem on lowered cars.
I'll be using 280zx struts which do not share the S30's strut angle (510/ZX are more vertical), so what works for Z will probably not work for my set-up, but the info on LCA location should help me.
Thanks.