Comp check 340

I have a gauge with about a foot and 1/2 of hose it fits past the headers no problem.

Also, if you switch to plaugs listed for a magnum motor they have a 5/8" hex and fit past the headers with a socket and extension with no issues either.

I use autolite plugs and the number is 3924 or 5224 for stock heat range and 3923 for one range colder. The 5224 extends the plug a little further into the combustion chamber than the 39xx plugs and is what Autolite lists for magnum motors starting in 97. The thread, reach and the heat ranges are the same as the bigger plug listed for the LA engine.