An ms 361 and the ms 660 are two completely different things,the ms 361 is a 60cc 4.6 hp chain saw with 47mm bore and short 34mm stroke,it's clutch doesn't engage until 3,500 rpm and doesn't make it's power until around 8k so not well suited to a single speed setup when our engines can produce more hp and torque much lower where it's needed.The ms 660 is 54mm bore and 40mm stroke producing 7 hp (in it's case) so more potential power to be made but again not until higher up in the rpm range.Both can be adapted to our case with some work and knowledge sure but if you went to Millennium Technologies or L.A. Sleeve and had one of our cylinders prepped and plated It would perform better,last longer and bolt right on with no issues.Millennium's nickel,silicone,carbide treatment is stronger than nikasil and come's with a life time warranty so IMO money well spent with the best possible results.L.A. Sleeve uses nikasil and is a bit cheaper,not guaranteed to last but surely would out last the china chrome plating by far probably ten to one so again worth looking into.The little tricks likes cir clips used, better rings/piston along with a treated cylinder can produce just as much power if not more with alot less effort and similar expense.