I'm not sure that 318 heads had anything special for truck use. You might have exh rotators like the 360s had... But I don;t recall seeing them on anything besides 360s before. Regardless, basically every small block head is pretty close to it's simblings in terms of performance. All 318 port size heads are similar, all 340/360 sized are similar. So really I'd say do what ever you feel like with/to them.
