Since Warranty is your strongest point have you tried talking to the Guy's at Scoggin-Dickey in Lubbock? They have a great reputation for their motor's. and you might be able to talk to them about what you want (power) what you need (good Vacuum) and I believe they will cam swap and still maintain factory warranty.
I have had no first hand experience with them, Only word of mouth.
https://sdparts.com/category/crate-engines
Might be worth the Call.