How do I create two eights = 140 as a tempo marking?

Dorico
1

How do I create this tempo marking? Stravinsky Rite of Spring

2

MusGlyphs font is your best bet there.

3

This is quite spectacular indeed. Too bad I cannot use this font in the (Shift+T) tempo box.

4

The tempo box is semantic, and therefore it’s going to be limited in what it can parse.

You can set tempo and hide it, then type as system text, bold.