If the car need's Lower Compression that Means the Engine is not Originally a Supercharged Block and is sitting on stock N/A Compression Ratio it would not be worth it as it is a top swap only with just too big of a boost pulley to keep blowing the head gaskets, to stop that from happening you will need to change to the supercharged block (can tell if heads are off if it is a supercharged block as the pistons will be dished stock are flat) and replace all accesory's to said block. Now if you still want to go ahead with it there are a few things you will need be for you attempt to do it / take to a mechanic
#1) a Valve regrind kit (Good one to get bit expensive is the Mace regrind Kit $240 or so with head bolts).
#2) a set of head bolt's or stud's.
#3) Depening on kms say over 250.000 replace Valves.
#4) ether replace whole water pump or if still good a water pump gasket kit
theses are for if you do it you're self.
#5) fuel line puller can get a cheap plastic kit at super cheap auto.
#6) a 1000kg Jack to help lift Both Engine and gearbox out (Yes Both i have done it once be for just pull an engine its not easy to get the bell housing to the engine lined up)
#7) a Decent engine hoist and Metric and Imperial socket's and spanners.
#8) Spare Time and Hands to get the motor back in.