Wow, it must be nice to win the lottery. On the other hand, how often do you get a chance to buy a new tractor set up with everything?
You do realize that the basic tractor with far less extras will do 99% of everything? It would be fun to see what a BASIC list of extras would look like. Just so you know, everything on SmokeyDog's list would make my list of basics. Particularly a seat upgrade. I'd add a cheater for the SSQA, a tarp, and a spinner knob.
I don't quite follow your thinking on the engine HP vs PTO HP. But for what it is worth, here is the way I see it; tell me if this sounds reasonable.
Engine HP is an advertising spec. Good for beer bets. Basically it is a bare engine back in in the lab on a stand without any parasitic losses - it may not even have to run a fan or water pump... all that is done for it. By doing some indirect measurement - like fuel consuption vs BTU out - a geek comes up with a nice unverifiable HP number. Nobody I know is going to take their engine out and measure HP that way. In fact, there probably isn't any way to hook up to that engine to measure HP directly...
The adverting dept. is free to use whatever Engine HP number they feel their geek can justify.
PTO HP is a whole different animal. PTO HP is verifiable by any mechanic in most full size tractor dealerships. They use the number for warranty claims. The dealer may not routinely measured his compact tractors, but they probably can. You can probably pay to have yours measured next time you are in there.
A PTO dynamometer that reads out in HP is a basic piece of diagnostic equipment that it is hard to do without for Ag tractors - there is really no other way to check if a tractor is making proper power. So it's a common tool in any large tractor dealership. Having a PTO shaft makes a dynamometer check quick and easy to do for any size tractor with a PTO.
The shop manual has a number for PTO power and your tractor should darn sure match that spec.
On going up hills... Most tractors I know won't pull top gear to full RPM on even a slight grade. Our big tractor won't do that and the
M59 sure won't. Anything over 2% and I don't even bother to try. And ours is at least a ton lighter than what you are proposing. Now it will pull top gear on a smooth flat road, but not at any grade. Luckily the
M59/62 with HST plus has six speeds. You'll find one it will pull.
rScotty