Head gasket choice
from what i can see with the head gasket issue was with the offset of the feed hole in the head on the 1jz is dangerously close to the edge of the 2jz head gasket, apart from thaty they are identicle... the best way around this is to weld the oil hole in th head up and re drill through the chanel at 45 degrees giving the head and block a larger mounting face. at the moment it is only 1mm with a 2j gasket, 1.5mm on a 1jz gasket. with the amount of 1.5jz conversions happening in australia this is the most common way to olve the issue.
however in saying that, the only reason you need to build a 1.5JZ-GTE is because you already have a 1JZ-GTE and u wanted a 2JZ-GTE. otherwise it is just as cheap, if not cheaper to just buy a 2JZ-GTE.
the blocks are 99% identical, just the extra height (30mm) thats why a 1JZ-GTE oil pump will fit on a 2JZ-GTE block and work, only real differences are the timing belt length, idler pulley angle, and the length of the water neck off the water pump. the head is vastly different though.
my question is
whats the reason for using a 2JZ-GTE flex plate and stall converter? Why cant you use the 1JZ-GTE flex plate and stall converter for a 1.5JZ-GTE?
im currently rebuilding a 1JZ-GTE cresida to a 1.5JZ, already finished the convertion from a 7M-GE to a 1JZ-GTE, had to pull the head off to replace a melted valve so now its just to go bigger.