Roof rack mounting for strength questions

[NJM73]

I want to build a roof rack for my 71 and I am torn between doing several mounts to the drip rail or do mounts on the roll of the roof. I'm looking for whatever will give me more strength and support. I want to move my 37 inch spare (about 100lbs) plus my highlift, shovel and a few other tools out of the cargo bay. It needs to support this, as well as myself (200lbs) or someone else. I like building things overkill if I can, and I want it to be safe to carry 400-500 lbs. But I don't know what the limits of the drip rails, or the roll on the cab would be. Any advice or pics would be appreciated

PS my drip rails look in good shape, and I do not mind drilling through the roof