I've never seen anything that defininatively explains the difference between the HO52 and HO72. To the best of my knowledge, the HO52 has a 9.75 ring gear and the HO72 has an 11 inch.
With the "load bolt" I would lean towards it being a HO72, but who knows what changed throughout the years.
There are a number of kits out that that will convert a rear axle to fron axle use. The biggest problem I see is with the axle shafts. You'll need someone that can make a shaft with the Eaton spline pattern. I'm sure there's someone that can do it.
Here's some knuckles. Your tubes are 3 1/4" so the 3 1/8 are what you would need.
http://www.reidracing.biz/off-road-p...a-60-inner-c-1
http://www.reidracing.biz/off-road-p...ering-knuckles
14 bolt kit with lots of info.
http://www.cranehiclearance.com/crane_017.htm
I've heard of guys using Dana 50 knuckles from a Super Duty and fitting them to 14 bolts or D60s also.
Start choppin bro!