Engine lock up

[Lenny51]

My 8ba just rebuilt is on the test stand now it started for may be I minute & stoped the battery was very weak from spinning it over to get oil pressure up we charged the battery about it gave half a spin the nothing
thought the starter was hung up took the starter out thied to turn the flywheel with a 3 foot bar wont go eather way any ideas going to start tomorrow by taking the oil pan off yes there is 5 quarts of oil in it

I wached the guy put every together every thing turned freely new pistons & rings
new valves & springs new Isky cam new adjustable lifters all new bearings
new timing gears bored 60 over crank cut 10 under balanced offy heads
block magnfluxed