I started assembling my ms660 kit last night. =) Using all farmertec parts from the kit. No "upgrades" at this point.
Crank case halves in the oven at 245 degrees for 20 minutes. Crank in the freezer for 1-2 hours. Used the supplied crank case gasket, with no silicone or anything on it.
Put flywheel side of the case on the crank shaft first. It slid together like butter, by hand. No tools required. I worked quick though. Assembled within 10 seconds of removing from oven/freezer. I then set it on blocks, put the gasket in place, and got the pto side of the crank case out of the freezer. It was around the 45 second mark I think when I slid it on. It had some resistance and bound up tighter than I could press on by hand. I tapped on the top of the case with a rubber mallet to get it together. The case finally snapped together around the 1 minute mark, but it pushed the PTO side bearing most of the way out of the crank case. I then used a heat gun and laser thermometer to heat the case around the bearing to about 200 degrees, braced the assembly on the flywheel side crank shaft, and used a large socket and rubber mallet to pound on the outer race of the bearing and was able to get it seated down to where it should be with about 5 hits.
Note: If I do another kit, I am going to leave the case halves in the oven for 25-30 minutes, and freeze the crank for 5+ hours. With a slightly better temperature differential, I think both halves would have slid together by hand.
Test fit piston and cylinder before installing rings and 1184 to base. First, the cylinder contacted the side of the crank case so I had to fix that with a dremel as was illustrated on this thread a few pages back. After the cylinder was sitting flush on the crank case seating surface, I checked squish. Without the supplied 0.022" thick base gasket, the piston contacted the top of the cylinder. (enough that I couldn't rotate it through by hand) This was with cylinder bolts tightened. I then installed the base gasket and checked again. It rotated freely. Checked squish with solder through the spark plug hole, it measured 0.028". So the spot that I measured isn't the lowest spot....but it does rotate freely.
I then installed rings, and put 1184 below and above the base gasket and got the cylinder torqued down. Then backed cylinder bolts out one at a time and applied blue lock-tite and reinstalled.