Front mounted snow blowers are not a good idea. I have myself seen a 60 or 70 hp Belarus broken in two when the front mounted snow blower caught on a piece of concrete hidden under the snow. Most tractor frames aren't designed to handle loads in that direction and they just snap. It has happened often enough that nobody even thinks of front mounting a snow blower anymore. Another problem is the shaft bringing power to the snow blower which ends up hanging under the tractor all year round and reduces ground clearance. To my knowledge Porsche are the only tractors with a power take off in the front as well as in the back.
If you have snow drifts too deep for the tractor to go over towing a snow blower you should get one of those big wheel blowers that are open in the back so you can reverse into the drifts.
Personally I cannot see any needs for hydrostatic shift. I have never driven a tractor with shuttle shift though I know some English built Internationals have it. If the gear levers are reasonably ergonomic there is no need for shuttle shift in my oppinion. However it is a great advantage if the clutch pedal is ergonomic. Some tractors have very unergonomic cluth pedals.
Your description sounds like an International 533 would be ideal for you. The hydraulic system is excellent. It has power steering and synchronized gear box and a separate PTO clutch and is generally very comfortable to drive. A neighbur has one and in my oppinion this is the supreme 45 hp tractor. Completely beyond comparition with anything else ever manufactured. However I don't know if they were ever sold in USA or if they were made only for the European market.
For easy access to spare parts a 100series or 200 series Massey Ferguson would be great. I own and drive a MF 165 since 10 years and think it is a fairly good tractor. "The worlds best prototype" is what I call it. It has plenty of details which aren't quite as optimised as they should be but in all mayor respects it is a very good tractor. I am rebuilding the motor at the moment and with 50 years of use on it I haven't found any obvious weak spots only even wear. MF 165 and 168 are at 58-62 hp a bit larger than you thought of but I rekon the extra weight and power is a great adwantage when shovelling snow with a front loader. However all of them do not have power steering and you must have power steering for front loader work. You also need a concrete counterweight that fits the three poiint hitch.
The smaller Massey Ferguson tractors like MF 30 and 35 and 130 and 135 have all proven quite unsuitable for front loader work. The front end gets too heavy and the narrow front wheels sink into the ground however large your counterweight is.
Volvo BM 400 or 430 would be ideal for you but they were never sold in USA so they are out of question. So are Valmet 502 and 602 which are both excellent tractors though spare parts are running out even here in their homeland. They were never sold to USA either.
Ford 3000 or 4000 or 5000 would fit your needs. The 5000 is significantly more powerful than your description but it isn't too large in my oppinion. The 2000 has proven too small for front loader work in the snow. Theese are all mighty good tractors though they have one significant weakness. The motor. They have no cylinder liners. Those triple idiots at the design office designed treactor engines without cylinder liners. This means that when the cylinder bores get worn (which they usually are by now) one must bore them out very accurately to take aftermarket dry liners. This is a rather expensive process. If it wasn't for this flaw the 1000 series Fords would be excellent.