Sounds OK. You most likely are off a few degrees since most engines were not timed to fire at UDC/TDC.
What year is your 216 (car or truck engine)?
What year is your flywheel?
Usually there was also a ball embedded in the flywheel and that is the "timing mark" and that is a different location than the triangle (or other TDC/UDC) mark.
http://chevy.oldcarmanualproject.com/chevyowner/51tom100.htm
