* Performance Considerations: 305 heads generally have smaller combustion chambers and smaller valves than 350 heads. This will affect performance. While they'll bolt on, you'll likely see a reduction in power and potentially a less efficient combustion process, especially at higher RPMs.
* Compression Ratio: The smaller combustion chambers of the 305 heads will increase the compression ratio in the 350. This might be beneficial in some cases (e.g., a naturally aspirated build) but could be problematic if the engine isn't designed to handle that higher compression. Detonation (engine knocking) can occur with too much compression.
* Exhaust Port Size: The exhaust ports on 305 heads are usually smaller and may restrict exhaust flow compared to 350 heads, impacting performance.
In short, while they'll fit, it's generally not a recommended practice unless you have very specific reasons and understand the performance implications. Using heads designed for the 350 will yield better results.
