You can buy the genuine Toyota 9.8:1 pistons, but ironically they are more expensive than fitting 1mm oversize 3t-c pistons. That of course is a new price. I happen to be selling an early 2tg that is fitted with 9.8:1 pistons. You can buy that if you want.
If you do have bent valves, fit valves from an 18rg. They are cheaper and marginally larger.