"safe to ride" is a statement from authority. We're random people on the internet who can't even see your wheel and are not qualified to make a judgement for you.
A rim designed for rim brakes will have a rim brake track. If you don't have that, the rim is NOT intended for rim brakes, and won't have enough thickness. A rim brake will initially work, but the touchpoint will wear quicker, and will have less thickness so you'll be risking a rim blow-off much sooner.
Its possible that you'll write off the rim in short order, maybe as little as 1000 km.
Or it may survive for a long time - we can't tell you what's "safe" We're showing you the risks, its up to you to to make an informed decision as a competent adult after weighing the risks/benefit.
My advice would be to sell the track wheels on, and buy a suitable set of wheels used.
Its likely your track wheels are for a 120mm OLD, so using them in a road bike may require frame bending too, and then you're always going to need 120mm rear wheels. Its just not worth it - buy some boring normal wheels which will be cheaper than uncommon track wheels. You might even come out ahead financially.