Finding a 'W' motor isn't as hard as finding a good one (truck block that isn't i a thousand pieces) that you can afford. I can not remember where I read it, but someone is planning on recasting a new high silicon content four bolt main blocks for the 409. Edelbrock already has new aluminum heads and intakes for the motor and Comp Cams even added a bunch of grinds to their catalog for the W motors. Tin might be a problem (valve covers and timing chain), but not the oil pan, and there are oil pumps and pistons available. Use a BBC rod and crankshaft turned down to the 409 journals and you have a brand new 409 (or considerably bigger) that is stronger by far than the original.