I built a 318 about 25 years ago and put a 340 windage tray and used the DC bolt kit. The tray hit the crank and I had to use two flat washers under the head of the 2/4 capscrews. I measured those caps later when I replaced it with a 340 and found the cap to be about 1/8" shorter at the bolt surface. I haven't had any 318 engines since, nor measured any caps. Based on one 318 block and one 340 block, that's what I found.