decking a 360 block

Decking the block (or heads) requires the intake to be milled so it sitt and lines up properly. You are now married to that combo and any change will require more machine work. Flat top pistons on the other hand are not expensive, you can weight the old and new and if your lucky, the new ones weigh a little more than the old and you can lighten them so you dont need a rebalance of your crank ($$) and you can use your old longblock. Choose your path, both are gonna be ~200 and up. Now a Cam that is ground to your low comp motor may be the other option, they will factor in your low compression and get you a grind that maximizes cylinder filling. ITs only money.