Here ya go.. I used my calipers also and they don't lie!

6.625 root to stinger tube
2.625 inlet tube to stinger.. same
1.140 fattest part of pipe before weld to weld fattest across pipe weld to weld 1.710
1.240 fattest two halves
1.500 mounting post .. center of post to stinger
8.00 overall pipe length.. weld to stinger end.. not including J
3.210 overall width.. header end .625 across J to weld
12.500 overall length .. .625 end around to stinger end (outside)

I sure hope you understand this! Because it sure looks funny if someone reads this.

Looking at the two measurements I would guess you have the HP pipe but not sure.
Also are boat club (Marquette Boat Club) is having are IMPBA race July 1st at 167th Cicero Ave, Oak Forest, Illinois. Not that far from you. I will be one of the judges for the race.