You mention you've had great success with Hellrazors. Have you gotten complete pass throughs with them, or only partial pass throughs? If its a penetration issue, a single bevel, near 3:1 ratio two blade would be a good choice, such as a Grizzly. They come in many different weights, so finding the right head should be easy. If penetration is not an issue, a 3 blade would probably produce better blood trails. Personally I would choose a Magnus I, Zwickey Delta, or a Simmons Tree Shark if you want great 2 blade blood trails.