I use an engine hoist to put the motor in the frame. Bring it in from the side then add a strap inside the frame rail and remove the outside strap. Continue to the other strap and do the same.
Once the motor is in it can be positioned to fit the motor bolts. I put the bottom bolt in first, then the motor can be rotated to put in the rest.
I made a mount for the return filter that fits inside the right rear motor plate. Simplest in line with the hose routing from the motor to the rockerbox feed.
The head uses pillar bolts on all locations. The exhaust pushrod tubes have to be in place before the head is fully set down because the cutout in the cylinder is different between exhaust and intake sides.
The pushrod tubes are adjusted for 0.020" clearance with only the top square o-ring installed.
Once the pushrod tubes are adjusted the bottom o-rings can be placed over the tappet blocks. I use Loctite 515 on the square top and the two bottom o-rings to help them seat. A dab of grease on the ball end of the pushrods helps keep them in the tappet socket.
The valve adjusters are backed off and the rockerboxes set down. A magnet on a screw driver is used to pull the pushrods in place under the pin.
The adjusters are turned down enough to hold the pushrods on the pins as the rockerbox bolts are tightened.
A dental mirror can be used to check the pushrods are in place.
I tighten the four 5/16" bolts evenly until the rockerbox just contacts the head. The valve screws have to be turned out as the bolts are tightened since they were screwed down previously to hold the pushrods.
I replace the three socket head screws at the lip of the rockerbox with button head screws which have about 75% more area under the head. Sealer is used under the heads of these screws to keep oil from going down the threads.
With the electric start and no kick lever, the valves have to be adjusted by turning the crank with the sprocket nut or the rear wheel in high gear.