I have used a K&N on a Mikcarb, and I do run a Goldstar straight-through. If that is any help to you....
First, you need some way to support the back of the carby so the rubber inlet tube isn't supporting the weight..you will get air leaks which will mess up your jetting and add confusion. The cone filter lets in lots of air so you need richer jetting to compensate or you WILL ruin a piston, which WILL put molten shards of metal all through your engine. I have experience with that.
Before I knew better, I ran a cone filter and free flow muffler with the stock jets of 25 pilot jet, P0 needle jet, clip on the 4th groove and a 120 main jet. That was too lean. An engine rebuild taught me the lesson the hard way.
I live at sea level so the jetting I use is a P2 needle jet, the needle clip in the lowest groove and a 127.5 main jet. The pilot jet is 27.5 That is appropriate for my situation. However I now use an Ace Canister, which I think is better than a cone filter. The carburetor is drawing from a supply of still air.
Anyway, I hope this is of some help to you.