Will my legs hold up?

Snatch
Heavy Single
53x3
63x2
73x2
83x3

As average for me as this progression looks, it was a good night. Being rational, and not allowing myself to get frustrated with the 83# plateau, I know that my form is actually getting better and better in small ways, even when the total weight is not soaring up.

Snatch Balance
bar x6
53x3
63x3
68x1
73x1
78x1
83 fail


WOD
16 barbell lunges 83#
16 ring pull ups
200 m run
14 lunges
14 pull ups
200 m run
12 lunges
12 pull ups
200 m run
Time: 11:09

The rx'd weight for this was 40% of my back squat 1RM...So I did put 103 lbs on the bar and I tried it once. With one lunge, I was sure that I would fall over with the bar on my back if I actually tried the WOD with that weight, so I went with 83#. Even at that it took considerable effort to make it all the way down to one knee and then get up again.

And these lunges did me in. After going up and down the stairs all morning after this wod, my legs feel ready to give out by the time I get to the last step.