Welcome from from KC.
I have a 1986 GMC. It Also has the same engine number on the block. According to the what I found on the internet it goes like this.
1968 thur 1979, 350 or 327 cu.in.
145/375 hp. 2 or 4 bolt main.
Truck or hi pregormance.
I hope that helps.
That a lot of variables but it's...