1982 350 break-in. is my oil heavy enough?

i've been taking my truck for a spin every chance i get, to try to break in my remanned 350. it functions fine, but it seems to run hotter than i'd like. i think i may need heavier oil, considering the extra friction inherrant in break-ins and the warm weather we've had. not brutal, but consistent low 100s. i thought 10w-40, but the shop recommended 10w-30. i found no cooling system problems when i was reinstalling it, and the stat is a new stock temp. would changing to 10-40 or 20-50 be enough to help this out.

maybe it's my imagination. the last time i did an engine swap was many years ago, so i'm really rusty on it. thanks.

denny is right on it... probably your first 500-1000 miles its going to run a little hotter hotter than usual... and also yes lighter oil will dissapate heat better than heavey oil.... if you are really concerned about the temp.... run water wetter... it will make you run a little cooler... on average about 10 degrees sometimes all the way up to 20, its a pretty neat formula redline has been selling lately... it costs about the same as a gallon jug of coolant... we've been using it at the shop a lot lately... mainly on cars having overheating problems with customers too cheap to have their whole cooling system cleaned out and such.... seems to work