What are you putting in? a 2 or 3mm? Some guy on SF put a 2mm in his 1jz-ge and it lowered the compression a little. Enough to run a few more lbs, maybe 2-3, but nothing dramatic. Id just swap in some GTE internals or go aftermarket when you do your headgasket since the head will already be off.
Dunno what a 1.5jz compression ratio would be stock though, since its half of a 1j and half of a 2j lol.