I have found such sites in the past - some notes
here.
But currently none of them seems online. This
site, which has been down for months, used to show the IR images with an altitude scale in metres - nice...
What I find however is that, in the context of an aircraft which can climb to say FL160 plus, the accuracy is not an issue providing you avoid fronts. With non-frontal weather, the tops are rarely above FL140 and if they are it is really obvious on the IR image. And frontal weather has tops usually well above that kind of operating ceiling so this facility is not useful.
Nowadays I plan my IFR/airways flights almost entirely with MSLP charts, tafs, metars, and the IR image on the morning of the flight. I have stopped using the GFS-data-plotting sites like Meteoblue because one just sits there worrying about stuff which doesn't exist on the day.