You will have to find the engine code stamped on the engine and decode the information. The first place to start is to get all the numbers and there locations on the engine and come back here.
Nov 20, 2009 Rating
engine in your 78 vette. by: Ned
they came with L82 & L48 350's If it is original engine the numbers are located at the right front of the engine block pad in front of the head. It will have the last six matching of the vin number code plus a 3 digit suffix code STAMPED ON THE PAD. such as 423567 and CMS OR CUT etc. You may want to research the story of the 1978 corvette web page...it explains it all. good Luck !