Did all 273's come with a steel crank?

Yep, I believe they did. Every one I've ever seen has been anyway.

Yes they did.
I believe ALL classic Mopar mills had steel/forged cranks until the early 70s. The 273 went out of production in model year 69.

I have pulled apart a couple 69 273s and neither had a steel crank, my 68 did have a steel crank.

And in the LA 318s I have never found a steel crank, 67-99. I have heard of other guys finding them in 318s but I never have and I have torn apart TONS of em looking

Evidently 273/318 cast cranks were phased in in '68, the casting numbers are 2658268 or 2658393.

This comes up about once a year. The 273 and 318 used the same crank and rods, with a heavy wrist pin in the 273 to make up for the difference in piston weights. So there are at least two model years of 273s that should have a cast crank although remember MOPAR, never say never!

Also, I cannot imagine a 273 making enough power to put a cast crank in danger, that short stroke and decent sized bearing journals are plenty strong.

R.