This one as far as I know is a Chevy. It came in a Chevy, but wasn't the original motor in it so I'm not 100% sure. I had the casting code off the block somewhere but I can't find where I wrote it down.
gm made 4 engines whit 350 cubic inches Buick easy its the one whit the distributor in front . Olds is the one whit a oil fill tube in front. Pontiac is the one that you can unbolt the intake whitout taking the distributor out finaly the chevy most 350 chevy have 3970010 as a casting number hope this help you
Bare bock for a 350 is about 110lbs, iron heads are about 55 lbs each, crank adds another 60lbs. Tack on manifold, carb, rods, pistons, balancer, oil pump, distributor, fuel pump, water pump and other misc items brings you up to about 500 lbs. Finish dressing the motor out with all of the accessories and starter and you have a 600lb chunk.