I already changed my registration almost a year and a half ago. I was a Republican right up until mid-September 2006 and then changed to a Democratic registration.
It was this Iraq war, and my growing opposition to it, that caused me to change parties.
So, it doesn't matter who the Republicans nominate, because I'm not voting for any of them in November.
The Republican I would be most comfortable with would be Mike Huckabee, but even that would be a stretch. Although, his fiscal liberalism scares even me and I'm pretty far left fiscally myself. He seems to be about a -9 or -10 on the Matrix scale, where as I'm just at a -5 or -6.
Huckabee has a strange blend of economic views. As governor of Arkansas, he carelessly raised taxes on goods and services hundreds of times. As a candidate for POTUS, Huckabee has proposed an elimination of all taxes but one -- the sales tax. This "Fair Tax" plan would actually raise taxes on the poor and the middle class, and help the rich, who mainly pay income and capital gains taxes. His views are hardly liberal, but his record is hardly conservative.