I measured the depth the pistons of my 357 are in the hole, and they are around .04 to .05 for all them. Is this really bad? Should i get the block decked? Should i just run it this way? I will be running 64 cc heads with flat-top pistons, with a compression ratio around 10.

 

That's a little more than usual, but not a problem. I'd leave it alone and run it.

 

.040 - .050 deck height works out to very close to 10:1 compression with your combination of parts.

If you zero decked it, the compression would jump to 11.15. You would also need to check piston to valve clearances.

 

I was going to deck the block, in order to curb detonation problems. I've heard that a compression height around 0.04" with head gasket is optimal.

 

For the amount of difference it will make, you won't be able to tell the difference. At the compression in question, that degree of finessing that detail is a waste of time and money.

Just run it, lots of factory motors come out that way, and work just fine.

 

Install your heads with .015" shim gaskets (felpro)
and you'll be fine 9.85:1 -- 10.08:1 depending on deck height.

 

My personal choice would not be shim gaskets; the extar couple of tenths of a point of compression aren't worth dealing with blown head gaskets all the time.

I have never yet taken apart a single motor built with shim gaskets - not one - that didn't have at least one combustion leak between cylinders.

A 9.9:1 motor with intact head gaskets will outrun a 10.1:1 motor with blown head gaskets, every time.

Use Fel-Pro 1010 gaskets and enjoy your motor longer.

 

I was thinking of maybe using the Mr. Gasket .018" gasket, what do you guys think? Is it a good gasket?

 

Same issue. Don't. Just go with the stuff that won't break. The tiny difference in theoretical performance that you'll never notice is a fair tradeoff for the lack of reliability, which you definitely will notice.