I took the same style values as you, and it looks quite good:

but it looks better with a svg symbol. With the standard >
I get this:

The saved style looks as follows:
<renderer-v2 symbollevels="0" type="singleSymbol">
<symbols>
<symbol alpha="1" type="line" name="0">
<layer pass="0" class="SimpleLine" locked="0">
<prop k="capstyle" v="square"/>
<prop k="color" v="99,5,130,255"/>
<prop k="customdash" v="7;2"/>
<prop k="customdash_map_unit_scale" v="0,0"/>
<prop k="customdash_unit" v="MM"/>
<prop k="draw_inside_polygon" v="0"/>
<prop k="joinstyle" v="bevel"/>
<prop k="offset" v="0"/>
<prop k="offset_map_unit_scale" v="0,0"/>
<prop k="offset_unit" v="MM"/>
<prop k="penstyle" v="solid"/>
<prop k="use_custom_dash" v="1"/>
<prop k="width" v="0.26"/>
<prop k="width_map_unit_scale" v="0,0"/>
<prop k="width_unit" v="MM"/>
</layer>
<layer pass="0" class="MarkerLine" locked="0">
<prop k="interval" v="9"/>
<prop k="interval_map_unit_scale" v="0,0"/>
<prop k="interval_unit" v="MM"/>
<prop k="offset" v="0"/>
<prop k="offset_along_line" v="0"/>
<prop k="offset_along_line_map_unit_scale" v="0,0"/>
<prop k="offset_along_line_unit" v="MM"/>
<prop k="offset_map_unit_scale" v="0,0"/>
<prop k="offset_unit" v="MM"/>
<prop k="placement" v="interval"/>
<prop k="rotate" v="1"/>
<symbol alpha="1" type="marker" name="@0@1">
<layer pass="0" class="SimpleMarker" locked="0">
<prop k="angle" v="0"/>
<prop k="color" v="255,0,0,255"/>
<prop k="color_border" v="0,0,0,255"/>
<prop k="horizontal_anchor_point" v="1"/>
<prop k="name" v="arrowhead"/>
<prop k="offset" v="0,0"/>
<prop k="offset_map_unit_scale" v="0,0"/>
<prop k="offset_unit" v="MM"/>
<prop k="outline_style" v="solid"/>
<prop k="outline_width" v="0"/>
<prop k="outline_width_map_unit_scale" v="0,0"/>
<prop k="outline_width_unit" v="MM"/>
<prop k="scale_method" v="area"/>
<prop k="size" v="2"/>
<prop k="size_map_unit_scale" v="0,0"/>
<prop k="size_unit" v="MM"/>
<prop k="vertical_anchor_point" v="1"/>
</layer>
</symbol>
</layer>
<layer pass="0" class="MarkerLine" locked="0">
<prop k="interval" v="9"/>
<prop k="interval_map_unit_scale" v="0,0"/>
<prop k="interval_unit" v="MM"/>
<prop k="offset" v="0"/>
<prop k="offset_along_line" v="5"/>
<prop k="offset_along_line_map_unit_scale" v="0,0"/>
<prop k="offset_along_line_unit" v="MM"/>
<prop k="offset_map_unit_scale" v="0,0"/>
<prop k="offset_unit" v="MM"/>
<prop k="placement" v="interval"/>
<prop k="rotate" v="1"/>
<symbol alpha="1" type="marker" name="@0@2">
<layer pass="0" class="SimpleMarker" locked="0">
<prop k="angle" v="0"/>
<prop k="color" v="255,0,0,255"/>
<prop k="color_border" v="0,0,0,255"/>
<prop k="horizontal_anchor_point" v="1"/>
<prop k="name" v="arrowhead"/>
<prop k="offset" v="0,0"/>
<prop k="offset_map_unit_scale" v="0,0"/>
<prop k="offset_unit" v="MM"/>
<prop k="outline_style" v="solid"/>
<prop k="outline_width" v="0"/>
<prop k="outline_width_map_unit_scale" v="0,0"/>
<prop k="outline_width_unit" v="MM"/>
<prop k="scale_method" v="area"/>
<prop k="size" v="2"/>
<prop k="size_map_unit_scale" v="0,0"/>
<prop k="size_unit" v="MM"/>
<prop k="vertical_anchor_point" v="1"/>
</layer>
</symbol>
</layer>
</symbol>
</symbols>
<rotation/>
<sizescale scalemethod="area"/>
</renderer-v2>