k&b 7.5cc early carburetors

[Taxman32]

I got two early k&b 7.5 cc marine inboards. It has front exhaust and the carburetor is diff. then anything one on thie website at least i can't find a picture for it. It looks like a square body it has no low end idle just high end. It mounts to a circular plate w/ two boltsthen the circular plate has a smaller circular pipe probably about 1/2 long that goes into the back of the engine. I am trying to buy 2 new carbs. but don't know which one to buy? But they run ok with the carbs. i got now but my old high needle valve o-ring was going bad on both so i pulled them off. Could this make them run more poorly? I'm looking to make them run god again. So tell me what i need to buy
thanxs
ben