[squidtone]

My64GTO,
In my case, the "dish" center plate would have been way too hard to pound down to get the proper fit. The offset had to be corrected by almost 1/4 inch. It was way easier to make a flat plate.
As for the welded block-off I made, I must admit this little "passage" was a head-scratcher. The function of that gap doesn't make much sense...it doesn't look like it was meant to flow coolant, but the fit was sloppy however. I'm wondering if it was simply to help mesh the two plates together. There was a tab in the dished plate to fit, but it was easier for me to just seal that gap by welding a "patch".

And yes, the 11 bolt system does seem so much easier.