the likelihood of your being able to deal with a 600pin BGA is phenomenally miniscule. I design with FPGAs as part of my job and an ordered not touch one of those. You need to be able to be able to do at least a 6 layer PCB with buried vias and a grid of pads at 0.5mm or less pitch. You then need to place and solder the BGA when there is no way to get the heat to the pads to melt the solder with the only way to verify the soldering quality being an xray machine.
I can design the board, place and solder the BGA, but we can not justify the purchase of the xray nor desire the expense of sending all our boards out for the test.
You should concentrate on an FPGA that is NOT a BGA.
LVDS is a common interface that is readily available on FPGAs
**broken link removed** has LVDS and PLL and, and, and it is instant on flash.