You can try that, for sure, but in my experience TrainerRoad doesn’t necessarily give you a good feel for what different zones should feel like due to the lack of any long intervals at or below FTP in most of the plans.
When basing my plans on the ramp test, I could still complete 98% of the workouts in SSB for example - 10 minutes slightly above threshold is doable after all - but it was soul-destroyingly hard and my progress came to a grinding halt. This was with an FTP 3-7% too high.
So if it was me, I would redo the test, and start wayyy lower than you think you should, like 250W maybe. Hold that for 20 minutes. Then slowly ramp your effort up, like 1W/minute at most, until you feel the effort start to change drastically. Then back it back down a few W just to be safe, ride until you’ve got a minimum TTE and start ramping up again just to feel what it’s like over FTP.
You don’t have use the average power of the test as your FTP btw - if you spend a decent amount of time at a steady wattage and can feel a drastic change if you go up 5W, you can call that your FTP.