probably a canon XL body with an EF convertor (this in itself gives a 7x focal length conversion factor in 35mm lens terms, so if you had a 300mm canon film lens it would become a 2100mm) and a fast L series telephoto lens, cost will be dear - very very dear depending on what body & lens you specify, keeping the camera steady will be extremely difficult at huge magnifications, the depth of field will be minimal, so manual focus will be critical
Sigma do a 50mm-500mm lens, not particuarly fast, but would give you a whopping great focal length of 3500mm!, ef convertor is £350, an XL kit will cost you anything from £600 for a used XL1 to £6k for the very latest high definition XL body.
You would also want a very good tripod (manfrotto 500 series at the very least) plus some sandbags & windbreaks.
