Making car blueprints in Blender without getting one from the Internet

I model cars so that I could feature them in my Roblox game but my mom noticed that the blueprints I got in modelling the El Camino SS is copyrighted because she saw a watermark that belongs to theblueprints.com. I earlier followed a tutorial video about how to draw car blueprints for yourself in Blender in which the YouTube link is this one: https://youtu.be/PSqiswfVb5k.

However, I do not seem to do it because Google lacked certain reference images for the views (excluding those photos that had a perspective view) about the said car. I did blueprint outlines from a blueprint image of a Mazda Rx-7 FD but my attention is on the 1970 Chevrolet El Camino SS which the blueprints I got is not just copyrighted, but also there are some inaccuracies in the blueprint.

If I will draw the car blueprints from the given reference images, how can I make them look orthographic enough so that I would not have difficulties in modelling the car and more importantly not getting copyright-claimed?

I also wanted my blueprints to be different from the tutorial because the tutor left a margin on the outlines and I wanted the image size to be 1:1 and it should at least fit the top and side view outlines of the blueprint. I will provide the blueprint I used in modelling the El Camino SS.

The blueprint I used:

Try this site. Much detailed pics.

and

Good enough for blueprints

I am no layer, but i dont think you got an copyright issue is you modell a car from it for non commercial use.