Finding Velocity in Verticle Circular Motion without Time/Period

So the problem goes like this:
A 75Kg pilot is doing a verticle loop de loop that has a radius of 778m. Assuming that there is no air friction, what is the velocity of the pilot at the top of the loop de loop if he experiences 0.510G?
The Answer is 107 m/s.
I've spent an hour on this, rearranging the formula, trying to work it backwards, but I still can't get the right answer >.< Help?

http://physics.bu.edu/~redner/211-sp06/c…
I found the equation below at the website above.
ΣFr = N + mg = mv2/r → N = mv2/r - mg.
N represents the downward force that the pilot feels at the top of the loop.
On the ground, the downward force that the pilot feels is his weight.

Weight = mass * g
0.510 G means the pilot feels an acceleration of 0.510 * 9.8 = 4.998 m/s^2.
Weight = 75 * 4.998 = 345.85 N

345.85 N is the downward force that the pilot feels at the top of the loop = N
At the top of the loop, the pilot feels like he weighs 345.85 N

374.85 = 75 * v^2/ 778 – 75 * 9.8
374.85 = 75 * v^2/ 778 – 735
Add 735 to both sides
1109.85 = 75 * v^2/ 778
Multiply both sides by 778/75
1109.85 * 778/75 = v^2
v = (1109.85 * 778/75)^05 = 107.3 m/s