I'd take about 1/3 of what you have - roughly 15lbs, and dissolve it into 6 gallons of warm water.... It *should* (every honey is a bit different) get you in the 1.080-1.085 SG range..
I usually dissolve the honey on the stove, but you literally only want warm water - if you're dissolving the honey and you see bubbles/foam start to form on the top of the honey-water, turn the heat off as its warm enough for your needs and warming it further only strips the final product of more delicate aromas and flavors.... Takes a little while, but everything with a mead does..
So i'll fill a 1-gallon jug and use that measured out water to dissolve the honey, and when the honey is all dissolved, subtract what you used to dissolve it from the overall (6 gallons) of water used in the batch, and add the remainder.
Dose pectic enzyme, make yeast starter, wait 12 hrs
Dose nutrient/energizer & pitch yeast
Ferment out to "dry"
Rack to carboy & degas if you have a vacuum pump
Rack off gross & sur lees
Allow to clear on its own (expect 6-9 months clearing.. might clear sooner, but..)
Rack when clear
Age as long as you can stand it, adding k-meta to keep oxidation at bay
Drink... someday?