Torque specs:
http://www.toyota-supra.info/forums/84660-post8.html
Make sure you chase the threads in the block and lubricate the fasteners thoroughly with a GOOD moly lubricant.
Were both the head and the block inspected for cracks, pitting, warpage?
Generally if a HG is already leaking I don't recommend re-torquing as an attempted fix... You're liable to trap moisture and open yourself up to cavitation of head or block (and with an old HG possibly compromise the reinforcement rings around the coolant jackets and cylinder bores). If the block's really expendable then feel free.. if it works, then you've lost nothing as it's only going to be in there for a year or so and if not well, you're still pulling it.