steel shim head gasket

I just did my slant 6 with the steel shim gasket and did use KopperKote and re-torqued too. FSM said to do so. No leaks on the lifter gallery; the head was surfaced and the block checked for straightness and found OK.

Re-torquing is an old habit from building engines for me. My '62 FSM does not mention re-torquing, but I did it anyway. Found that all of the marginally loose ones were on the lower row of head bolts; not sure why.

For the OP, if you are getting leaks with the composite gasket, I would suspect warpage in the head and possibly the block. I personally would not use the shim gasket without surfacing the head and making sure the block is surface or is straight. No problem with using the RTV on the lifter gallery side, but it won't hold as well as KopperKote or Permatex #2.

With turbo-ing; the lower CR with the thicker composite gasket might be of benefit to you. But I don't know where you are at with boost, etc.