Sal---A thicker gasket is OK when one wants to lower the CR for things
like using lower octane fuel, and the like. However, I don't think it's
a good idea to depend on this gasket change alone when going to forced
induction. A lot depends on how much boost you are planning to run, the
design of the system, and the octane of the fuel you are going to use.
If the early head hasn't been milled to less than 3.460 you might get
away with running boost pressures of 5 lb.* with pump gas of 91 octane.
More pressure than this I would suggest to expand the budget to include
the later head, (7.75:1) gaskets and manifolds. Prepping the block at
the top of the cylinders is also good, so the later gasket can fit down
into counterbores. All of this helps make a forced engine stay
together.
*Easy to set desired boost with turbos that have a waste gate.
Superchargers generally require a change of pulleys to get a specific
pressure. (You didn't say)
If you still want to go with a steel plate under the early head, I'm
sure there are specialty gasket shops that can accomodate you. You
would need to add around .080 over the stock gasket thickness.
Dick
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