Is a pinasco 177 cast iron three port really plug and play?

Howdy from NZ

has anyone just bolted it on with correct jetting and done some miles

looks like another pinasco fiasco

Exhaust port opens at 106 and closes 246 ie 140 timing

transfers open at 123 and close at 228 ie 105 timing

the bore was only 2thou

that exhaust timing seems low at 140.....research says aim for 172

I had a sieze 10kms from home after careful running in and careful jetting

what do I need to do to get this kit running again It has been suggested to add a  3mm spacer and machine the head or barrel

It was described as plug and play.

 To go from 140 to 172 exhaust duration what do I do???....ie how many mm do I need to raise that exhaust port...or how many degreres should it open at to get 172 ......do I even need to do it at all and it was just bore clearance all along that caused the sieze??? 

Dremmel in hand a waiting your response  (instead of the spacer way of doing it)

help[!!!!!!