Do you have final say in all frame angles and measurements?
Head angles are getting slacker every year. Seat angles are getting steeper every year. For a while there was a trend towards short chainstays but now there is movement in the opposite direction towards longer chainstays and/or frame size specific chainstay lengths.
One example is the 2020 specialized enduro 170/170 travel, 64 hta, 77 sta, 442mm chaintays, with a very long 464mm reach and 1246mm wheelbase in medium.
https://www.specialized.com/us/en/s-works-enduro/p/171282?color=264085-171282
For last year's ripmo AF, the numbers are 160/147, 65 hta (slackened from carbon ripmo's 66), 76 sta, 435mm chainstays.
The latter is more of a long travel trail bike that climbs well, so numbers are closer to the average for trail bikes in 2019. Flip chips to change geo and adjustable chainstay lengths are becoming more commonplace.
Largely, this comes down to personal preference; higher speed riders tend to prefer slacker hta's. However, if you choose a slacker hta, this will reduce reach, which is already much lower than industry average at 412.5 vs an industry average closer to 450mm in medium.
So that's the thing: you can't really change one thing in isolation without it impacting other aspects of the frame geometry. Are you considering any other brands or frames? It's not clear how you arrived at the geometry for this particular frame. Are these recommended geo numbers or did you choose them yourself? The geo is very different from those of a contemporary frame.
There are now almost limitless options for very affordable but excellent emtb's, motobecane and commencal come to mind immediately.
