If you have a good 200 free, you should be able to hold on long enough to have a decent 500. You'll need a bit more conditioning, of course. And I believe it is important to do sets at 500 race pace on short rest so you get a feel for holding pace. I like to do USPRT sets. My USRPT for 500 training is repeat 50s holding 29 seconds or better on a 50-second sendoff. I do two sets of 30 of those. Of course, as designed by USRPT, I never do the full 60 because I fail out of the set. But that set gives a great feel for the pace and also improves conditioning.
If you have a good 200 free, you should be able to hold on long enough to have a decent 500. You'll need a bit more conditioning, of course. And I believe it is important to do sets at 500 race pace on short rest so you get a feel for holding pace. I like to do USPRT sets. My USRPT for 500 training is repeat 50s holding 29 seconds or better on a 50-second sendoff. I do two sets of 30 of those. Of course, as designed by USRPT, I never do the full 60 because I fail out of the set. But that set gives a great feel for the pace and also improves conditioning.