KB167 vs KB399

Well... I am not sure if you said what year your 318 is, sorry if I missed it but there are some different specs for piston deck clearance for different years. There are also different Compression heights for different years. Regardless the CH on the Keith Black pistons is 1.810 which is higher than any stock 318 piston. I am not sure if you were caculating this in or not. Because with so many variances this could put you between -0.015 and 0.020 but should not be less than 0.020.

Now with that being said, you would still most likely be better off with the dome pistons, IMO. Especially since you are using 340 heads, so you can out weigh the larger combustion chamber.

In my case I am goiing to use the KB167's and here are my reasons why: First off I am using "302" casting 318 heads that have a smaller chamber(Haven't cc'd them yet to know the specifics) and which are closed chamber. By closer to 0 decking while using flat tops and using the mopar perf. thin head gasket I can get really good quench and compression with closed chamber heads(May go to magnums later if I need more power). Only thing is I will have to watch my piston to head clearance. I also like the fact that there is less mass in the flat top.

I am by no means an expert so some one please point out anything incorrect I may have stated. I am planning on a decent 350+HP 318 build as well so I have been doing as much research in this area as possible. So good luck with the build! Awesome ride by the way as well, can't wait to see new pics of it when you have it up and running.