Regardless of who you talked to on the phone, the fact remains that with flat-top pistons and 64cc heads, a 383 will be over 11.0:1 static compression ratio. You cannot run that cam on 11.0:1. The motor will rattle like a can full of rocks from detonation and beat the pistons out of it.
If you want to run the grind that the guy you know chose, then change either the heads or the pistons or both. You need between 9.5 and 10.5 to use it. I'd shoot for 10.0:1.