I Threw a rod in my 73 240, and I am planning to drop my 280zx block in it with either my E31 head or my E88. I've been told by some muscle car guys that running 11.0 to 11.5 compression (an educated guess) is to high for premium gas. I figured I'd get some advice from guys with some knowledge about real cars before I went back to the drawing board, though. Any info would be much apreciated!!