I wouldn't get too caught up in whole "engine has to be this color" thing. Remember that there exceptions to every rule. I was of the understanding that the only engines that weren't "meant to be red" were the IH engines to set them apart. This would be factory fresh example of a truck. I know that in other trucks, different color engines slipped through and I can only assume the same for IH as well. So even factory fresh leaves the window of variance. If it is not a factory fresh build, then anything goes. Between repairs and possible engine swaps, the sky is the limit. I think that it is totally up to you. Black, red or even tan in my opinion would be just fine. I have seen inline Cummins in IHs before that were a combination of red and tan from having repair work done.