Woo hoo! Another 1/2-ton 4x2 Sub...
Make sure that you're looking at the correct engine. The GM long block that lists for $1295.00 is usually the one used up through 1985-- 2-piece rear main seal and old-style valve covers and intake.
1986 was a one-off year with old-style top end and new-style bottom end.
1987+ used the new style bottom end-- 1-piece rear main seal, different flexplate bolt pattern. It also used the center-bolt valve covers and TBI intakes.
Just thought I'd point it out in case you missed it. Good luck!