Sorry to resurrect this thread, but it's a good one. I just picked up a '71 Valiant with 39,800 original miles. It is really solid and has a fresh blue metal flake paint job. I'm excited to have it!
It current has the 198 slant six (yes, not even the 225!) and I'm a power guy so I've been diligently researching crate engines. ATK and Blueprint were on my short list, hence resurrecting this thread. I'm an automotive engineer of 21 years in the Detroit area, so I get pretty deep into the weeds on technical factors.
So... I really want a good bang-for-the-buck motor and I'm drawn to the Magnum-based 408 from Blueprint. My question / concern is that both Blueprint and ATK use the stock Magnum heads which are crack-prone. Why not use (or at least offer for extra) the aftermarket and stronger EQ heads (EQ-CH318A)? They flow better and are much stronger. Also, how much does it really save to go backwards to a flat tappet cam? Aren't there good roller cams that don't cost much more? The Magnum engine block is already set up for roller.
@Johnny Mac - would love any input! Really trust your insight. If that motor had the better EQ heads and a moderate roller, it would be a no-brainer. Could that maybe be a mid-level upgrade between that and the aluminum head roller 408?
