My thinking also, but if it's a steel crank, and out of a truck it's probably a 10.2 blk. If you can lay your finger between the top of the water pump mounting flange and it comes up even with the top of the deck it's a 10.2 blk. if not it's a 9.8 blk. 10.2 is an o'k blk. but cost more too build.BUT i would also be absolutly sure on the bore size that it's a 4.250 bore, because it could be a 366" motor.
JMO
Zip.