Crate motor 225 ?

The only company I know of that offers anything close is Mabbco Motors. They do offer some performance upgrades.

Dodge Chrysler 225 3.7 Premium Long Block 1967-1974 Slant Six - NO CORE REQUIRED - 1 Year Limited Warranty

If yours is an early car, you'll need the earlier part number for the right crankshaft register.