Take a look at my book For Cause & For Country and you will see a map on page page 311 which will show you exactly how the Federal regiments were lined up between Columbia Pike and Carter's Creek Pike. The initial assault blew the 50th Ohio and 72nd Illinois clear off the main line and the two companies of the 183rd Ohio also moved to the rear. Everyone else held their position(s).
It is doubtful Johnson's men ever encountered anyone from the 72nd Illinois because they slammed into the main line, not the secondary, or retrenched line, where the 72nd Illinois had rallied. Exactly what flags Sharp's men supposedly captured has always been a mystery. I certainly don't want to discourage you, but the answer is likely not in any regimental history or memoirs or anything of the like. If it's anywhere it's probably a letter. I spent 10 years researching my book and never came across a single thing which would indicate what flags Sharp's men took.