Th mopar guy

I don't know anything about them... my judgement is that it's someone making a living with Mopars and Mopar parts. Since you are in VA, why contact someone in KS for a block? The local boneyards are full of 360 parts.

Unless you want the 340 for personal preference or for possibly adding resale value, the 360 is a fine choice with MANY more used parts and more things like piston choices. The heads and valvetrain stuff all interchanges.

How do you plan to go about putting this together? What are your overall engine build goals and use? In that way, maybe some better advice and ideas on how to proceed will be forthcoming.