Skyscraper Zero Killer

Here as promised elsewhere is a Skyscraper Zero Killer puzzle - it's on an 8x8 grid, and has variously sized regions in which no digit can be repeated, and some (but not all) of the regions have a Killer sum indicated.

Enjoy - although I should warn that this one is reasonably challenging!

Hmm, now that I have four distinct SSZ puzzle formats (regular, VSR, Killer, Cryptic), I might have to ask for two pages in Issue 15 to fit them all in!