Radders

Hi all, Radders from the UK here, long story ill try to keep it brief! i bought a 1969 Camaro way back in 1982, drove it for a year and for a multitude of reasons garaged it ever since! 2 years ago i decided to do a full nuts and bolt restoration, the car is now back to everything standard, (spent a fortune importing OER parts) She is almost ready to go but i have an engine issue that is baffeling me; the engine will start and runs brilliantly from cold, oil pressure is around 45-50 (engine is rebuilt) water temp is a constant 79 degrees celcius (176 fahrenheit) then after about 20 mins i notice that idle become slightly erratic but still ok. If i now turn the engine off and wait say 10-15 mins, the engine is now so tight that the starter wont turn it over. If i put a torque wrench on the crank it will rotate but only at around 100 lbft!! (as the engine cools the torque gradually drops to around 65 lblf cold. I know this is too high but i put it down to a new engine. yesterday using a jewlers loop (eyeglass) i have noticed tiny pieces of what appears to be bearing white metal in the oil. for info, when cold the compression on all eight is 150 psi, i dont think this is a piston/ring issue, the crank and bearings are all standard size so no regrinds anywhere. if i restart after everything has cooled the same thig happens again, one final observation, when after 20 mins or so things get tight if you stamp on the throttle you do see what apperas to be a little oil smoke, but if i hold it at 1500 prm for instance no smoke, oil stem seals?

Sorry to all of you for the length of this post! i am running out of ideas and money!
Thanks, Radders