Trying to make this recipe

https://www.justonecookbook.com/wprm_print/baked-japanese-sweet-potatoes-yaki-imo

But it doesn’t turn out as good with regular orange sweet potatoes and I live in a regional town and I don’t know if my local Asian stores will have them because they don’t have websites I can check so I’m wondering is anyone knows which sweet potato type here in Aus is closest to the Japanese sweet potato.