I would do 91651-61022... 60 transmission mount bolt. High-tensile. Wide washer. Silver Zinc. Correct wrench size. I can sell you them for $2.47 each.
Not stainless... but for what you will spend on a custom bolt just get a whole extra set and replace in 10-15 years if/when they start to fade 🤷
I think most would be surprised to find that OEM Toyota hardware is actually often LESS expensive then generic. Especially if you go through a vender (like my business) that has taken the time to find various part numbers that are less expensive then others for what is essentially the same...