The 7010 was only powered with single cylinder engines and when Simplicity went to twin cylinder engines they made the front frame 2" longer.
There are re power kits that fit the B&S Vangaurd V-twin engine but trying to fit the Magnum boxer twin would require frame and engine plate modifications, hood reworking and wiring and power shaft mods at the very least. Kohler still sells the updated K341 single cylinder engine, which will bolt down without modification, you can get the flywheel adapter from simplicity for this( allis chalmers 716 part), the exhaust pipe to mate the oe muffler, and a few wiring and key switch changes and thats about it.
The small engine repower places have kits for more horse power and bolt in convienience but unless I was building a competition pulling tractor I would not even bother. Just my 2 cents