porting combustion chambers

how much cc's can you gain...5 cc's? 2 cc's? justwondering how big i can get them to lower compression

Depends on the design of the head and the water passages....

Ever think about thicker head gaskets?
[addsig]

it's my understanding that i don't want to forfeit my "squish" height which is at .06 as it stands

.060 is not going to quench at all!
So if you cannot get the piston closer than that, then the thicker head gasket is the better choice.
Either .035-.040 to quench, or get the piston as far away from the head as possible, like .100 or more.
Brian
[addsig]

now saying that i don't believe you..cause you build race engines...but what is the theory behind putting the piston .1 away from the heads? Also, this engine is designed for low compresion for the fact that i've got a 6-71 blower to put on it.

also, if that is the route i should take..what gasket should i use, and if my bore is 40 over...can i use a gasket that is 60 over?

and my first post was suppose to say "Not saying that i dont believe you..." cause i do

The best way to lower compression, is with a reverse dome piston, maintaining the quench. To properly quench the piston and head, you need to be around .035. Once you get over .045 you lose quenching rapidly and by .060 it's gone.
Now what happens is around .060-.075 of gap, you actually "trap" the air/fuel mixture causing an area not to burn properly.
This can lead to detonation, poor fuel mileage and power loss. Also high ex. temps from fuel trying to burn in the headers.
Brian
[addsig]

so how does the .1 gap help not "trap" the combusting gas. also, the pistons i have are of step dish design, just the dish isn't that big at 12.75 cc's

The big gap allows the air/fuel mixture to be burned instead of trapped, although the burn rate is slower which can cause detonation if the compression is too hight....like the 351/400M engine. Open chamber, low compression piston is far away from quenching anything...but if you bring the piston to zero deck and raise compression to say 10:1 and no quenching your likely to have detonation at sea level or maybe a hot day. Becomes worse when the load placed on the engine increases.

[addsig]