The 8mm shank greatly limits your options. 12mm is where options start to noticeably increase.

MGxx holders have to be that long for the clamp to work.

GTN holders have shorter heads, but the smallest shank I can find is 10mm - https://www.shop-apt.co.uk/part-off-...0mm-shank.html
Non-carbide holders can however be machined down pretty easily with a suitable cutter.