Front Motor mount (radiator core support mount, too):

Upper right assembly in this ilustration:
http://chevy.oldcarmanualproject.com/parts/1929_54/095.HTM

Figure 19:
http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0613.html

"I have an early 216 or 235 timing chain cover with the holes for the mount." - timing gear (& crank gear) cover
http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0622.html