Get a 360 and build it. For what you'd spend to get 400 hp out of a 318, you could build dang near 2 360's with 400 hp. Built a 390 for a buddies dart and had my little 360 in mine. Same gears and everything and I could walk away from him easy in high gear even if he dropped back to 2nd. Dont even wanna know what happened from a dead stop. As far as the 289's and 302's well they came with some compression and would scream with mild mods, a 318 aint gonna happen like that with out decking the block or changing the pistons to get some compression. 383 Chevys are popular cause they were one of the first strokers and used common GM parts. SB 400's are worthless???? Ha, got a 406 in a 69 Nova sitting here in the driveway, all GM except the pistons. Wanna come show me how worthless the 400's are? Them wheels on the wheelie bars aint skinned up for nothing.