I have been toying with this very idea. I have a very small diesel tractor - a Yanmar YM1110D, 13 hp. It is 4x4 and has a powershift transmission. It is an ideal mowing machine - except there is so little distance between the front and rear wheels that it is very difficult to put a belly mower on it. So...I've been thinking about how to run a front mount mower.
The physical linkage doesn't seem like such a problem - just need some arms pivoting from the front frame of the tractor with a cable and pulley arrangement to lift with the rear 3pt. I have a Yanmar belly mower on my YM1301D that lifts like this.
It seems to me the real problem is powering the deck since I don't have a mid-pto. I think there are two options for powering from the front of the tractor. 1) front electric clutch with belt drive (the belly deck on my YM1301D is driven this way 2) belt drive from a pulley bolted directly to the front crank pulley with a tensioning system rather than a clutch. A third option would involve powering the deck from the rear pto either with a shaft, or a long belt - but this seems difficult compared to the other two options.
It seems either option could work depending on whether you had access to a low cost electric clutch.
Incidentally, when I fabricated the mounting system for the idler/tensioner to drive the belly mower on my YM1301D, I made provisions to run the belt forward (by moving the idler/tensioner forward) to drive a front mounted snow blower. But it could be used to drive a front mounted mower.
If you get a chance, check out
my web site. You can see the lift mechanism for my belly mower. The front mount mower lift would be similar.
I also attached a photo of an older setup for a small front blade on my YM1301D. I used the cable/pulley arrangement for the lift from the rear 3pt.
If you go to my web site and then use the link at the bottom of the page to the 54" JD hydraulic blade page, you can see the belly mower idler/tensioner in its finished form. Painted even. The rectangular plates on which the idler and tensioner pulleys are mounted are removeable as an assembly by removing 4 pins. The assembly can then be moved forward about 5" and reattached with the same 4 pins. This aligns the idler and tensioner pulleys to run the belt forward (though I have no use for this feature YET...).