I'm not really building a "trail Jeep" I've already owned a few, if I was I would just keep the 258. This one is my 9th CJ over the past 35+ years and I'm looking for dependable power to hit mild trails, sand drags (about 3 miles from my house) Glamis sand dunes a few times a year and maybe 1/8 or 1/4 once in a while. The 343 build I've been reading on IFSJA put the compression with 343 pistons just under 10 to 1. So, I'm confused and asking questions. For some reason I can't post on IFSJA or I could ask Rick directly