carb swap/upgrade '75 cj5

Hey there folks,
I have a quick question...I am looking to swap out my stock YF for another,
or possibly upgrade. I am currently having problems with the current carb
and don't feel it is giving my enough on my 258. Not a huge engine, but the
YF came off of my 232 when I swapped the engines.

Question is, can y'all make recomendations for an engine appropriate, $$
conscious, mildly upgraded CJ (trail rig, but not extreme).
Currently running 31's but looking to grow in the not too distant future.
Also the diff's got 3.73 in it. Not sure what to look at for the fuel
delivery. Like I said, just feels like its falling short.

Brandon