You are welcome, Ivan.
I am glad if my information was any useful for your project.
Your understanding about the weights of 100 rounds of belted type 99-1 and 2 is correct.
About the Ho-5 and its ammunition, I find very few data.
According to "Nakajima Ki-84 Hayate" writen by Leszek A. Wieliczko,
weight of projectile of armour-piercing type for the Ho-5 20mm cannon was between 112 grams and 120 grams, while heigh explosive or incendiary type was 79.0 grams.
Which type projectile for the 84.5 grams out of 217.0 grams I quoted last is unknown but I think the 217.0 grams does not include links in my impression.