Eight cylinders in a 13 studs lenght, very nice Alex! Pity for the modified guides, I am thinking if there is a way to do it clean?
Your new con-rod piston guiding method clearly saves up a lot of weight and the con-rod acts more directly on the crank, I like the sound of that very much! I do not like the sound of the engine though, you might want to play a bit with the valvetrain configurations, the engine as it is now does not run too smooth.

Compared to your previous Challenger V8, how much torque does a new one produces, can you feel any difference?

Looking forward seeing the final version, I am sure you will be able to balance the valve timing :)

Ivan