I've used a lot of 1528 and 29 cranks since one of the best oval track builders in my area showed us his collection of cracked cranks.
They're cast of course but seem to hold up as well as anything short of a 4340 crank, and I've bought a lot of them on Ebay for a hundred or less. Then to had them cut down to 2.45 mains and 2" journals offset ground to 3.780 or better for a cost of $300ish here, less than 200 for a standard 383 turn. We do have a couple of real crank magicians in our area though. I'm fortunate to live close to Charlotte but if there isn't really accommodating crank machinist who loves his work, where you live you might consider a complete balanced rotating assembly. A lot of people are using Scat and Eagle cast but I've had no experience with them.
Another advantage of the original 400 crank (1528/9) is that it was originally balanced with heavy pistons. So far I've never had to have Mallory with one. That saves a chunk of money. And all mine have been smooth even at 7000 which is about as far as I've turned a 383. Without really nice heads the 383 has produced most of what the heads can deliver at just over 6000. I'm thinking something on the order of a well worked set of 993s, or 906s< (somewhat better), as you said you were staying with iron heads. But that makes for good torque and HP#s.
Good luck with the build, I'm looking forward to hearing the results.