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Is this engine original to your car? I can't help you with who to go to, but, make 100% sure who ever does your rebuild does not destroy, modify, mill, or otherwise change the stampings on the block pad.
As the saying goes "You get what you pay for". While a crate seems expensive they really are a bargain when considering warranty and your down time.
I rebuilt mine myself and I still ended up sinking about $1200 for stuff in it (gaskets, rings, bearings, seals, etc, add up) and had about 15 months of downtime since I just worked on it here and there on select weekends.
I would recommend starting with Lamar Walden Automotive in Doraville, GA.
Rob and the folks there are the only shop I let touch my cars. I'm in the Greenville, SC area, but found his shop when I was rebuilding my 409/425 engine in my 63 Impala.