You can add a vacuum controlled switch to unlock converter under high load conditions.
Superior makes one adjustable from 1" hg to 6" hg, about $32.
My 200-4R is configured for 4th gear lockup only, and I ran with a manual switch for a while.. then realized that with it locking only in 4th, the manual switch was kind of a moot point....
as retro said: 12V+ (source) into the normally closed circuit of the brake light switch, back out of the brake switch and into the pressure switch, sourced to a ported vacuum location (same as the dizzy) then to the plug on the trans.
The vacuum switch allows automatic disengaging of the lockup while climbing a grade or under WOT conditions to prevent lugging/pinging. letting off the throttle or otherwise taking away the load will allow the converter to re-lock when vacuum conditions return to normal.
'84 SS, 103K (back home after 4 long HARD years)
'94 RCSB Silverado (193K daily driver)
'96 BBB Impala SS (84K garage queen)
'12 H-D FLTRXSE (36K parked)
'70 Pontiac Grand Prix Model J 400/TH400 survivor car (103K)