I've done a ton of these air cleaners. They work with both carbed and EFI Sportsters. Super cheap & easy so I thought I'd share.
4" air cleaner assembly from Auto Zone. 12 or 13 bucks.
Cheapy carb mount from Jireh, Ebay, J&P (or whoever is your fav)
This is what you'll find in the kit from Auto Zone.
The flange on the backside has to go.
Cut it off with a cut off wheel, hack saw or whatever. It's aluminum so it cuts easy.
Position it on the carb mount bracket.
You can see that the hole in the air cleaner backing plate is a bit too big to drill holes for mounting so I use a file to knock out notches.
Again, this part is aluminum so it's pretty easy to do. Just be patient and keep test fitting it...you don't want to notch it too much. Get comfy & file away.
It'll attach with the carb mount bracket bolts & the washers secure it tight.
The filter sits flush in the backing plate so the bolts will be in the way.
Give the filter the same notching treatment.
Install the stud that comes in the kit and run a nut down the threads to keep the filter cover from squishing when you attach it.
It's a crap shoot that the air cleaner kit comes with the hardware so pick up a 1/4-20 hex nut
Or an acorn nut
But I use a wing nut