Is it still a cable shift? Get the numbers off the drivers side pan rail if you'd like to know what it came in originally. It will be a 7 digit number stamped in the case. '80 should be solid lifter if it hasn't been changed. '81 started the hydraulic setup. There may be a before and after date that doesn't correspond exactly to the model year, so, anything is possible. The '81 with hydraulic cam/lifters used a different valve cover (and cylinder head) than what you have. That's why I figured yours is probably a solid lifter version.
