90 deg is not really the right bit for small text regardless of what toolpath strategy you are using, yes some fonts work better than others for small text & there are other things you can do to help machining, one font that I like is Shelley Volante but it has a very fine stroke width which often means that it won't carve deeply enough with a v carve toolpath even with something like a 30 deg 0.1mm engraving bit. I get round this by using a very small outline (offset) which makes the stroke a little thicker, practice will tell you what you can get away with before the font starts to look distorted.
Block fonts are generally best for small text but unfortunately they aren't very fancy
Other things that help is having a range of different angled engraving bits, I have from 10 deg to about 130 deg or maybe more. Flats on them make a difference to carving as well so some of them I have in a range of different flat sizes from 0.1mm to generally about 0.5mm but I do have a couple of 60 & 90 deg bits with up to 3mm flats.
Some other things that can help with machining small text, use a sanding sealer before carving, this helps to prevent chipping, slow the feed & speed rates down which can also help with chipping especially if your machine is not particularly rigid. Your machine would fall into the not so rigid class in my opinion.
Make sure you are using sharp bits, I would suggest keeping some bits just for small text if you tend to use v bits quite a lot, also try a forum search as it is something that has been discussed before.
Sure others will chime in with some useful info that hasn't already been mentioned