The winch in question is most likely a 2-speed Mile Marker 9000.
The main problem with the MM's is that the stock P/S pump ins't really up to the task. Since the Jeep in question currently does not have PS, that would be an added expense. Are you running a stock battery? Have you upgraded the alternator?
The magnum winches are built by Warn but are using older technology. They use the older motors that Warn used back in the 80's and 90's. This isn't a bad thing, it jsut means it will take a bit longer. If you're stalling it out, we've got to wonder if it's being used properly or if you're trying to tug a cement truck with it. If you're only using the first or second wrap then you're not using the winches full potential. I believe it's something like less then half strength. With the use of blocks and pulley's, you shouldn't have any problems with lack of force.
Here's something to consider. Most of the guy's out west who do the trails in Johnson Valley, use Warn's. I don't think anyone uses a MM. For a trail like Suprise Canyon (closed) it was a winchfest. Basically all you were doing was winching. The majoriety of winches out there are Electrics. Although there was a time when the Ramsey PTO 8000 was very popular with Jeeps. They are rugid and practically bulletproof. The cool thing with a PTO is that the winch line is assisted by the wheels and tires. They will turn at the same rate if setup on the transfer case PTO. I'd take a PTO over MM's hydraulic anyday.
Oh and there's one more option. You can run a electric powered hydraulic pump. This really complicates the whole system and would most likely affect reliability. You'll probably want to run a inline P/S cooler so you don't boil the fluid. (A good idea anyway)
I've got a trusty Warn M8000.