Compression...

I called Indy Cylinder Head about my stroker kit regarding compression. Jim Hill said I might have to use double head gaskets as my compression with the Edelbrock magnum heads may end up with 11.0:1 comp. ratio. Does this sound right? It's a 360 Magnum block and I ordered their 408 stroker kit with dished pistons. He said the pistons are pretty close (I assume) to zero deck? Am I missing something here? Anybody had something similar to this combo?