Moving Parallel Python code to the cloud

Question

Upon hearing that the scientific computing project (happens to be the stochastic tractography method described here) I'm currently running for an investigator would take 4 months on our 50 node cluster, the investigator has asked me to examine other options. The project is currently using parallel python to farm out chunks of a 4d array to different cluster nodes, and put the processed chunks back together.

The jobs I'm currently working with are probably much too coarsely grained, (5 seconds to 10 minutes, I had to increase the timeout default in parallel python) and I estimate I could speed up the process by 2-4 times by rewriting it to make better use of resources (splitting up and putting back together the data is taking too long, that should be parallelized as well). Most of the work in done by numpy arrays.

Let's assume that 2-4 times isn't enough, and I decide to get the code off of our local hardware. For high throughput computing like this, what are my commercial options and how will I need to modify the code?