It’s worth keeping a look out on Ebay for right angle gear boxes. I’ve picked up a couple over the past year, one as a new spare unit from a Parvalux type unit and the other as a complete gearbox. Both 30:1 ratio. The pair cost £30 between them which is probably cheaper than buying the gears and having to make shafts, bearings etc. The complete gearbox I got is about 5 inches high, 4 across and 2 deep with an extra 2 inches for the shaft. Something like that should be easy to adapt.