A few points and pics to follow:
Casting imperfection on the crankcase initially blocked the bigger Malossi cylinder skirt from Penetrating the crankcase. Had to Dremel about an inch of slag. It's a risk, but oiled rags and simultaneous vacuum minimized Aluminum in the case. I'll change the oil promptly.
Rest of installation went smoothly, but spent an hour figuring out the weird decompression mechanism.
Buttoned up and re-hung the engine from the frame. I thought I had everything necessary to fire it up, but Click-click. D'OH! Engine ground strap is not "Optional". At least I remembered to connect the spark plug!
Fired up and runs, but idle was very low. Air screw needed at least 1.5 more turns OUT! This was weird, one would think more displacement would make the jetting Lean, not Rich.
Now there's a flat-spot just off idle. Otherwise it PULLS!
I promise not to post a pic of how much bigger the new jug is than the old one. Don't want Piston Envy on the board.