Its a GM 350 small block numbers on block are 16s436522 V0521ckx.

 

here try this http://www.nastyz28.com/sbchevy/sblock.php

 

No such casting numbers on Mortec.com for Chevy 350.

 

^ Of course those numbers don't show up there, those aren't casting numbers. The first set of numbers is his partial VIN.
The second set of numbers decodes as:
V - Flint Michigan engine plant
05 - Month (May)
21 - day of the week (21st)
CKX - either a 1972 200 h.p. 350, or a 1973 145 h.p. 350, or a 1976 180 h.p. 350.
The casting date on the bellhousing flange will tell which one he has.

 

found on the net 1972 Corvette engine. not 100% sure.... On the back of the engine 6GM and 3970010 and E46 , and it has an iron manifold with EGR .Need to know so I can buy a gasket kit and other parts

 

Casting date codes go from A-L (representing January to December)
E46 = May 4, 1976
That also corresponds with your build date 17 days later.

 

but that's all the numbers I found on the engine. anything else I can do?

 

Now those are the Chevy casting numbers for 1969/1980 350 block.

 

What else you want to know, what it came out of?
It's a 1976 L48 350, 180 h.p., out of a Vette, and was coupled to an automatic trans.