My memory is getting weaker by the day, there was an article a few years ago about converting clunk tanks on profiles to uniflow systems, any one remember what to do?

Simple, bend the breather line so the end is very close to the centre of the outside wall of the tank (which then becomes the "bottom" of the tank in flight) making sure it can't interfere with movement of the clunk feed line. Use a third line bent up to the top of the tank as the breather when filling and blank it securely after the tank is full.

I hope you have already tlried the search engine on this forum.  As there have been some pctures and posts of how to do it.  If I wasn't so lazy I would do the search for you.

Yet a quick search on "uniflow" coughs up no results at all -- not even this thread!!!

I've been using a Dan Banjok fabricated clunk on a profile. Works very well. Dan wire wraps and solders the breather line to the fuel pickup. Breather line outlet approximately 3/8" forward of fuel pickup. Breather outlet is made of 1/8" copper tube bent in an S. The straight ends are of sufficient length to provide a good solder joint on the pickup side and a tight mount for the flex tubing attached to the front hub tubing. (If I could draw a diagram and upload it, my description would be clearer.) The setup permits the pickup and breather outlet to move together with the clunk. I attach muffler pressure to the breather outlet, my preference. Others allow the breather inlet to hang free in the breeze.