As my 3vzfe sw20 had a blown head gasket i feel i should get the heads machined to increase the compression of the engine.
I've tried doing some research into how much i should get machined off the heads but i havnt been able to find any numerical values so any help is welcome.
 
Also if anyone knows a good place to get the machining done near Melbourne please let me know

If the head gasket has blown, also check the top of the deck near bore on the block, the 3vz motor has a habit of block cracking superficially, and if this is the case, the deck will need machining.

It was blown at cylinder 4, (the middle cylinder on the top bank) as coolant was getting into the cylinder.
I'm hoping that its usually the outer cylinders that call for block machining as the engine is still in the car.
Before I put the engine in the car i removed the heads and put a cheap ebay valve regrind kit through it without getting anything machined so I was blaming the gasket quality as per reason it blew so I'll be buying payen gaskets for reassembly.