if you have a 904 its hit or miss whether a good ol nippy-mini will fit or not. Just did TTI's on my 66 with a 904, clockable powermaster, and i still had to dimple the header ever so slightly. initially I tried a "large case" mini from a 92 dakota that i picked up 10+ years ago, cylinder 5 primary rested on the motor body. no go. Next was a "small case" from an 01 ram van, same story. Called TTI about it and they claimed it could be due to "jig variations"......well, understandable, BUT when a set of headers costs north of 800 duckets i expect them to fit, and fit correctly. Anyway, with my 408 the last option was a robb-mc.......surprise! wouldnt fit due to the block, and the 904. shouldnt be an issue on a 340. FYI the starter sits approx 7/16 of an inch lower/closer to the crank centerline than a 727 does. I measured 2 spare cases i happen to have laying around. Called RobbMC and shot him an e-mail. he updated his website, because evidently no one has ever tried it before......anyway. FYI!!
