Usual wall cupboard height is 720mm. This is what most people ask for. However 900mm makes use of that gap over the top of the cupboard that simply collects dust and grease. If you have a 720 high you get the bottom and mid shelf. If you opt for a 900 high you get an additional shelf. All wall carcases are 300mm deep.

However if this is to be sited over a sink you’ll need to allow for head space so do take that into consideration.

I don't like the standard recommended kitchen units eg 900 with 2150 and 720 with 1970, I dislike the proportions. We have tall 2150 units. I assume you mean 2300 total height with legs included? You could have 700/720 with them. As you have a sink you need to decide how low the unit can come. I think it's best if your having wall units they are all same height, not staggered to take account if sink.

The standard gap between your worktop (at 900/910) and the underneath of your wall units (without pelmet) is 490/500mm so for a standard tower (2120 inc plinth) you have 720 tall wall units and for taller 2300 towers (inc plinth) you'd have the 900 wall units so the wall units are at 1400mm from the floor.

But I think you're correct as you have a sink and need the extra height between the wall units and worktop. When I do a plan and if there's wall units over a sink I'd always have the wall units stepped up over the sink area if its a long run, if its just a short run then i'd have them all the same height.

Even with 720 wall units these would be at 1580 from the floor which still might be a bit to low for you if you're tall.