Should be possible, I believe. I'd ask @burke about allocation in Jetstream, but from my point of view it should be alright.
I'd argue this machine could potentially run other builds too (unless you have reason to be strongly against it). While one a single build should run on that machine, while it's idle I don't see why other builds shouldn't run there.
But reality is that, while the work is not so hard (it would be go to terraform, setup a new machine that now bootstraps ansible AND puppet), I will not have time to do that any time soon.
On the other hand, I'm happy to help someone willing to go that path.