how much too deck the block

[jodowii2]

plan. 258 stock bore and stroke. have a 4.0 head ive had .020 cut off
block is out for cleaning and was going to have it decked.
head gasket measures .040
have a crower baja beast cam on the way. as well as the lifters and valve springs they recommend.
this cam is supposed to work with stock pushrods, that being said. how much can i deck the block before pushrod length becomes an issue. how much will this change compression?

what would you all do?

[Cheromaniac]

Every 0.010" you shave from the block deck will require a pushrod that's correspondingly shorter to maintain normal lifter preload, and will raise the static compression ratio by ~0.15:1.
Normal lifter preload on these engines is 0.020"-0.060" (1/3 to one full turn of the rocker arm bolt from zero lash to the correct torque spec). If you shave the block deck and find the lifter preload is too tight, consider buying 0.025" shorter pushrods. The sweet spot for lifter preload is ~0.045" (3/4 turn from zero lash)