cub engine/ carb question

i have something puzzling, this '58 cub i bought had a carb on it which was bad, by bad i mean it ran bad and leaked gas from everywhere, a kit did not help it, it still leaked, and would not run right , so i borrowed the carb off the broke down 48, temporary, the 58 now runs ok, i ordered a new carb for the 58, the only american one i could find online was a zenith, i have seen posts here where some didnt like the zenith, but cant remember why, now the puzzle, the carb will bolt on and hook up ok, but when its on, i cant check the oil, the dipstick is too large to pass the carb body, it is black topped, and is a larger part than the 48 has, so i went and got the small one off the 48, it wont work either as it wont seat on the filler hole on the 58's engine,the hole is too large, so i took the zenith off and just for grins took it out to the 48, for what it has, which is a smaller dipstick, and filler neck it looks like the zenith will work on it,whats happening here, i thought the 48 and the 58 were identical engines? have i got a aftermarket filler assembly, or could i have a much newer engine block in the 58 chassis? how can i tell?

I bought a 47 Cub last fall that had a lot of crap in the fuel system. After cleaning everything and putting in a carb kit I had a lot of trouble getting the carb to stop leaking and the issue caused the tractor to run bad. I had it apart several times and adjusted the float level. Finally figured out I had twisted the float just a little bit and it was scraping along side the carb body. Once I fixed that and had the right level it quit leaking. There is not much clearance in that thing. May want to back to the original carb and check out the float more. Make sure it doesn't have a in hole in it (will hear liquid inside when you shake it). Make sure the carb body isn't damaged. You should be able to make it work with a kit.

ive already done that, apparently what i think happened is while it was being refurbished, i cant call it restored, as ive had to do too much to it to make it a reliable runner the hood and tank sat uncovered with the cap off in a sandy desert environment and the tank got some sand in it, ive had to take the hood back off and clean flush, clean flush the tank until it was clean again when i took the sediment bowl apart to clean it it was so corroded it fell apart in pieces, so thats new now, the inside of the carb didnt look much better with lots of corrosion, inside it too, since i bought this cub when the 48 went down i gave all the money for what i was told and shown was a fully done tractor ready to go , as i needed it right then, im finding out it wasnt gone thru completly , ive already had to do a full tune up and replace the coil and ballast resistor chasing a electrical problem, too

Go to Farmall cub.com they will help you with your cub.

If the 58 is the long oil filler pipe it is a struggle to get the cap past a Zenith carb. I HAVE ONE THAT IS THAT WAY, AND JUST AS IT CLEARS THE END OF THE PIPE YOU CAN MOVE IT JUST ENOUGH TO PASS THE CARB., BUT IT DOES RUB. oops, sorry about the caps lock. Does your new Zenith have an adjustable load jet? If so that is the wrong carb., you will need the fixed load jet to let the oil filler cap clear.