Looking to upgrade

I currently use a 60D & am looking to upgrade. Any suggestions greatly appreciated.
I shoot mainly motorsport/motocross with a 70-300 L series zoom.

For motorsports your primary options are to upgrade to either 1 series, or perhaps the anticipated but unconfirmed 7DII. A 5DIII has the focusing system you would want but being full frame you give up some reach.

70d is the most obvious choice, then the 7d. The 70d has pretty much the same AF system as the 7d, but you won't have to get CF cards (70d uses SD card). The 70d does 7fps.

Otherwise 5d3 if you have the money

It's all down to your budget! A 1DX would be the first choice - but it is a LOT of money! Closer to the real world a 5D3 or a 1D4 would be excellent choices (the "loss of reach" from the larger sensors is less than you may think). If your budget is a bit more limited the the 1D3 and 7D are very good options - don't be fooled by the low pixel count on the 1D3 as they produce very good images. I can't speak for the 70D as I have never used one though they look very good on paper.
I would suggest that you go for a higher quality used camera than a lower quality new one, especially with a 1Series. This is simply because they are built to last longer and generally have better auto focus.

I have a 60D. I considered upgrading to a 70D, but the incremental benefit is not worth the cost. If I was coming from a Rebel or something older than the 50D, I'd buy it.

Buy a lens or keep your ammunition for the 7DII. This is my opinion/advise.