I've a copy of the cake street article and their mod was intended to increase performance rather improve breathing I reckon, they suggest elongating the hole in the breather to commence it opening earlier before bdc. The article does not give standard dimensions of the breather unfortunately.
Scotts bike uses in the region of a pint per 150 miles, more when the seal has blown out (mine is nearer 300 miles per pint and does not smoke) and whilst his bike doesn't smoke much it does smoke pretty much all the time (not great to be following behind it!), it's performance is good and it's mechanically quieter than (dammit).
If the breather is standard then he might have to try new rings, maybe a rebore, but the possibility that the excess pressure is causing the oil consumption is worth thoroughly investigating first.