lowering CR on franken-motor-build

Have a friend who keeps blowing headgaskets.
The info.
1.6 block
1.9azz pistons
ARP studs/bolts top and bottom
~3bar of boost
running with standard oem 1z headgasket (3 hole) 1.3mm thick.
head and block is resurfaced.
unknown CR, but need to be lower.
Easy part is just to go 2xOEM 1.3mm headgasket, mabye o-ring the block to keep boost inside.
but will it hold when boost it dialed in (3.5-3.8bar ?
car is only being used as a quartermile toy

Other suggestions ?

Why not to just get a metal HG spacer and then separate a head gasket and use the top and bottom on the spacer like the VR6s guys do.

here is a product similar to what you would need: http://www.kineticmotorsport.com/products/KINETIC_MOTORSPORT_2_0L_ABA_HEAD_SPACER-494-302.html

piston machining? http://forums.tdiclub.com/showthread.php?t=101370

Is that an 1.6TD block? The AAZ pistons protrude higher than the 1.6TD pistons, has he got shorter rods in there? DO NOT USE A HG SPACER ON A DIESEL!

If he's running 1Z head gaskets on a prechamber engine he's using the wrong head gasket, he should be using the AAZ one.

What kind of head is he running?