There have been some recent posts on the Yamaha FG series guitars, FG730S in particular. I, too, have one and am quite pleased, although I am no expert.
Several forum members have written about changing their saddle to bone. Unfortunately most replacement saddles aren't quite long enough to completely fill the slot on the bridge. Some have added some shims to fill the gaps.
Here is a better solution:
Yamaha has a website, Yamaha24x7.com where you can buy spare parts. It isn't easy to navigate, but here are the part numbers, they are perfect fits, too. They are 75x3x10 mm genuine Yamaha parts.
regular resin saddle: QA079000 $3.06
compensated saddle: QC458900 $6.28 (exact same as FG730S original)
bone saddle: U9337909 $8.84
You will have to sand them to the desired height, but that isn't any big deal and there is plenty of info on how to do that on this forum and other guitar sites.
Hope this helps.
https://www.yamaha24x7.com/yamahaoms/Default.aspx