727 not shifting right

Was the stock valve body known to be good? If unknown it's possible the 1-2 shift valve is stuck in the valve body. A governor pressure test such as suggested will reveal if it's a gov or VB problem. If the gov pressure drops to less than 2 psi it should start out in 1st gear. If it drops but still starts in 2nd I'd look at the 1-2 shift valve in the VB