Usually, running thick head gaskets help make things ping, and can have sealing problems if you use power adders like nitrous or some kind of blower/turbo.

If you haven't bought the new pistons yet, check out Mahle, Wiseco, and Probe.  All of those companies make pretty good slugs, and will have something to meet your needs.

Thick head gaskets are kind of a stop-gap solution to the problem.  Thicker gaskets means more gasket surface area for pressure to push against, so it can lead to sealing problems.  It also messes with quench, and can cause detonation issues, making an already ping-prone engine have even MORE problems, despite dropping the compression ratio.  It all depends on your build.

If you're using power-adders like nitrous or a blower, go with forged pistons.  They are more forgiving, and will fail gradually instead of all at once, giving you a chance to fix tuning mistakes.  The trade off is that they are heavier (bad) and they expand at a different rate from your cylinders.  This means that when they're cold, they'll usually slap a little.  Still, good quality forged pistons aren't a big deal for Fords.  The 5.0 HO motors even came stock with them, originally.

If you're not using power adders, hypereutectic pistons are much lighter, and can offer you better long-term longevity.  That's partly because their low weight stresses bearings and pins less, but also because their rate of expansion better matches the cylinders, allowing closer tolerances, even when cold.

If you want to compare apples to apples, Hyper pistons and Forged pistons will fail at about the same point, when they're being mistreated.  The difference is that the Hypers tend to shatter when pushed past their limits, failing spectacularly, while Forged pistons usually deform and fail gradually instead of all at once.  Sort of the difference between a bullet hitting cast iron, vs. steel.  A round that doesn't penetrate steel will still leave a dent, causing damage, while the same round hitting cast iron will usually shatter it.

Either way, if you push things too hard, serious ping will mess your stuff up, especially with power adders.

You'd be way better off getting pistons to match your heads, so you don't have to run 'unobtanium' racing or av-gas to go places.  Using a big cam to help with dynamic compression (like Sal says!) is another way to help things out, but if you're running an automatic, or want good gas mileage, that may not be the best choice either.

If you just want a vicious weekender/dragstrip terror, then throw the old slugs in and put in a nasty new bumpstick. =)

It all depends on what you want to use the car for, in the end.  Figure out that part first, and buy parts to suit.

Nice to have you here, Retro!

 

On my 351W build, I ran negative deck height with a compressed gasket thickness of 0.042".  I used a 9.50 deck height with the later model pistons to create that combination without having to machine anything other than valve pockets.  I must be getting old because I cannot remember the exact amount the pistons stuck out of the block.  I think is was about 0.005", which really helped keep it from pinging and picked up a few extra HP due to the extra squish tightness.  Ernest is still running that same engine and that buildup was in 1998 as I recall!.  That engine never used a drop of oil.