4th gear is a seperate gear has nothing to do with lockup
on the turbo regal lockup is controlled via the ECM and with ecm control it can only lockup in 3rd or 4th ..ecm uses speed signal from VSS and lockup should occur at around 48mph and disengage at 45 or whenever the brake pedal is depressed and provided the trans is in 3rd or 4th which the ecm can tell using the two switches inside the trans.
if you lockup the converter manually (grounding the F pin at aldl) lock can only occur in 2,3 or 4 (regardless of speed or signal seen at ecm) but not in 1st gear as there is no fluid flow in 1st for lockup engagement
running a lockup on a non lock is no good and should result in the lockup staying engaged all the time ,
there is a cheap kit (transgo 7-ccv
http://www.summitracing.com/parts/trg-7-ccv ) that easily converts the pump to nonlock
it can be installed with trans in car by dropping the pan and removing the TCC solenoid , remove the retainer snap ring and disc , pull out the stock valve and springs and install the transgo part , and you could put the solenoid back in or remove it (your choice) and close it back up
and when you take converter off remove the oring and the checkball assembly from the input shaft ,note some builders remove the check valve even on lockups to increase the lockup speed)
and depending on chip you run dont leave the tcc connector unplugged as you may still need the trans to tell the ecu what gear it is in for 1-2 2-3 timing and fueling