You need more cam with that kind of compression, a good start would be Comp's 280H. As for springs, you'll need to see what you have now, plus what studs are on the heads. Have they been converted to screw in types? For just about anything hotter than the 268H, you'll need screw in studs, guide plates will depend of what 289 heads you've got. If they're the pre April 66 heads, they'll have pushrod guide slots and won't need guide plates under the screw in studs.