I couldn't see where your tiedown points are on it, but I'll assume they're on the front A-frame of the trailer. Play it safe--use four tiedown straps (not rope) and either take the two front straps around the sway bar or around the lower control arms. Cinch them down tightly. If you can modify the trailer, I'd highly recommend putting some chocks at the front to run your front tires up against. They provide an extra safety measure. At the back, if your car has the tiedown brackets, use those for the rear--again one strap at each corner. If it doesn't have them, run them around the rear axle. Granted, the car is lighter without the engine and tranny and so you could get by with just one strap on the front and one on the back, but why take a chance?
When useing the tiedown straps or even chains and binders the best way to tie any load down is by crossing them in front and back,Your load/car or what have you will never move. Use 4 straps and cross them, leave the car in 1 st gear or park and the EM brake on..When tightening hook up a strap fron and back first so that the car is steady, release the brakes and put the car in neutral, instal the other two straps and tighten both front and both back . After you get it as tight as you can set the em brake and put the car in either park/auto or 1st, manual.