I have the same issues with my MK1: totally new engine that runs well but still blows smoke after 300 miles. Two things have made a positive change;
1. the crankcase oil feed banjo stud Will describes was not correct, and using a stud with a smaller restrictor orifice reduced over-oiling and head leaks
2. the crankcase breather banjo stud orifices were way too small....the engine was simply unable to breathe .....I opened out the banjo stud and this made an immediate improvement. The crankcase must have been over-pressurising
However, the engine still puffs, and I am told to be patient up to 1000 miles and let the engine run in ( and take a view then). The current smoking suggests oil is also coming from the bottom end still, not just the top. Also, I get oil pooling on pistons....I think that's the nature of the beast and the only way to avoid this is to fit seals to the guides....I may do this in time.