Here is my selection of straps for 351, I believe anything brownish or tan will work fine.
However, thickness of the strap is the key. Most of the OEM straps are quiet thin, at the same time 351 head is bulky and thick, and its thick in wrong place - on the back. I felt it was disproportional on OEM shiny gator or JV. But this brown calf is almost 5mm thick and balances watch nicely, and its not about the weight, but about proportions. I put it on few months ago and did not change since.