I think you will have closer to 9.75 cr if the block has -0.020" deck height, which is typical. 10.2 cr with a zero deck.
Still way too high cr for that cam and the load you are going to put on the engine (big heavy truck).
Plus 193 heads are terrible. You would be better off with a set of 882's, 76cc heads.
with 9.75 I would use a cam in the range of 218-224 degrees at 0.050". Like a compcam 268H or 270H.
If you reduce timing it may work, but mpg and power will be reduced. And may make it run hot.