High spec comp should be 145 to 150. At that level, leak down will be around 2 or 3%
Leakdown at 110lbs comp will be some 80%-90%. Any less than 90% is rebuild time.
You simply will not see 50% leakdown at 140lbs. Could be you had a good test for comp then a bit of a piece of crud ended up fouling a valve. Run the motor to full temp then test again. Ane the whole idea behind a leak down test is to determine where the loss is occuring, valves int or exh or rings or head gasket or a combination.
I doubt you would have any potential to start the motor at 50% leak down, and then if it did would run like crap and certainly would not idle.
You got some bad data due to procedure or instruments.