Deck height ...

1/2 the crank stroke + rod pin-to-pin length + piston comp ht. + whatever the "advertised" piston deck height is (usually a - #). All these #'s will be right beside the 440source kit # you ordered.

i.e.

4.25/2 + 7.1 + 1.43 -.010 = 10.645" deck ht.

You need a block with a minimum of about .010 MORE than that so it can be properly squared and leveled.