What do you think?

I've run the XE268 in a 9.8:1 360 (early small open chamber heads milled a ton), the XE262 in an 8:1 360 with factory 308 heads, and the 268H in a factory '68 340 and then an 8.6:1 318. The XE268 is a great all purpose cam. Using it in a 318 will be a little more lumpy than the larger displacements, but it will run fine if you're truely 10:1. The 268H passed emmissions for 3 years (CT idle inspection) and had a bit more ragged idle. But again, I got it to pass emissions with some careful setup. So it's radical sounding, but not really radical. It dod pull to 7K rpm, and with the low compression 318, with 2.02 valve X heads and stock pistons, there wasnt too much of a feelable loss in torque (in a '74 E body, 3.23 gearing and a 4sp). I broke the 340, swapped the cam and top end into a core I had, and ran that for a year. They had dropped the emissions testing for that car at that point. I doubt it would have passed. The XE262 is in my truck, and it idles smoothly at 650rpm in the low compression '87 360. It pulls pretty good, but it's all done at 4500 in that truck (1 ton w/33s and 4.10s). Given the choices you have, I would go with the 268H. It wont get into any detonation problems with junk gas, it will sound good, and the small valve/small port 302s are a real nice match for it. I ran a stock '71 T quad intake and carb. A Performer 318 with a 650ish carb would really be a nice combo. The XE268 might just give too much cylinder pressure with 10:1.