I don’t think a mid-year start is as viable an option as Cochrane makes it out to be.
On the one hand, if they can produce a contract with a manufacturer to run at any point in 2013, then their existing manufacturer is going to ask when they should only receive support for half a season before switching. So the manufacturer will either ask them to change sooner, or leave it until the end of the year. The end of the year isn’t an option for the new manufacturer, who will want to get involved as soon as possible. So they’re back at square one, entering at the start of 2013.
As far as the engines go, I believe they’re actually quite similar. Both use V8 engines with similar specs, but might need a bit of tweaking to work. At the very least, they won’t need to build an entirely new engine.