Looking for a 5.3 or 6.0 w/ AT trans pullout in NorCal

[MtotheIKEo]

I have a 73 Chevy truck that I inherited from my grandpa who bought it new. I want to drop in a newer FI motor to make it nicer to cruise in, just don't know where to look for the motor/trans. The few times I have looked have turned up prices all over the map for mixed bags of parts. Ideally I'd like to find a motor/trans/ECM/accessories package just to make it easier on myself. What is a realistic price range for either motor combo? Anyone in Nor Cal have a source for these?

Thanks for any help.