You won't get the gear range with any 8 speed IGH that you have with your derailleur system, but the closest you will get is the cheapest option among 8 speed, that being the Sturmey Archer unit. I've done a fair few IGH conversions of all flavors, and my least favorite platform to work with is a mountain bike. (Excepting Rohloff hubs, which do play very nice with MTBs.)
However, one of the main obstacles would not apply here, that being getting a large enough chainring far enough inboard to achieve proper chain line, and still clear the chain stays. You will need a very small chain ring to get low enough gearing with this hub, as first gear is direct, all others are overdrive.
You could probably use the granny ring on your current crank set, andget the chain line to work out pretty close.
Now, before others start ringing the alarm about extreme torque input at low ratios, I'll point something out about the SA 8 speed. 1st gear is a direct lockup across all 3 internal stages, so no stress is borne by the gear train or the shift pawls. I believe it would be perfectly safe to gear it with a 22 tooth chain ring and a 23 tooth cog PROVIDED you never use any gear other than 1st for hard climbing.
This chainring/cog combo on 26 x 2.2 tires would get you a gear inch range of about 25 to 82. pretty rideable range.
Also, the SA unit can be set up for 135mm old. I have one set for that width. If I ever build another, I'll use tha disc brake version, whether or not the bike has discs as the non drive side bearing is further outboard.