XR274HR-10 in 318

The stock cylinder heads will need extensive machining for anything anywhere even close to that .538 and .534 lift. The stock vale retainer to guide clearance may be good for all of .460 lift on a good day... And besides that, if the bottom end is stock with around a 9.0:1 compression and you're committed to the 302 heads, no good will come out of a cam anywhere near that large. I probably would be shooting for 10.5:1 compression with that particular cam. Care to tell us what it's going in?