Hello and welcome to Just Answer,
If the oil is coming out at the rear of the engine on the drives side beside the distributor then the most likely cause is the oil sending unit. It could be the intake gasket but the oil would come out rather slow due to the location of the seal.
The sending units can leak from the threads or from the bell.
Chevy Enthusiast
11 Years in the field, Shop owner, ASE Certified (Expired)