Well, let's get this discussion going so you can reliably get out on the road. Let's start with the idle circuit:
1. Find your fuel filter(s) by following the fuel line away from the carbs. There might be more than one filter and they may be on each end of the car (front/back). Make sure there aren't any kinks in the fuel line causing loss of fuel. Replace any fuel filters that you find - they may be full of crud and causing a loss of fuel such that it idles OK but can't operate at much above idle 'cuz there ain't enough fuel getting to the engine.
2. Changing the idle jets won't affect any change in the raw gas smell when stopped. That is usually caused by a gummed-up pilot valve in the float bowl leaking fuel into the bowls and overflowing when it's parked after running. (also, sometimes it can cause black smoke under acceleration because of running rich - Do you see any smoke?) Sometimes you can detect a stronger smell on one side of the engine than the other when recently shut off, and THAT pinpoints which side needs attention. Look around the outside of both carbs after it's been running and now shut off and see if any of the carb seams are leaking by looking for a slightly darker, wet color on the outside.
To service the pilot valves you'll need a service manual for the carbs: There are a couple on the CB Performance web site by Bob Thomlinson, one for Webers and one for Dellortos. Pick whichever one fits and find out how to clean and set up the pilot valves (you end up setting the float height and that's critical for good operation so maybe something for an experienced mechanic). This might be something for someone with carburetor rebuild experience to do the first time. Maybe ask if you can watch so you can learn how to do it. Maybe buy him/her lunch for showing you. * See #4 and maybe add that to his/her list to do for you, too.
3. Jets: the 50's you have should be in the ballpark. If anything, you could drop down to 45's but if it was running OK before on the 50's then it should be OK now with them. Instead and assuming that it had been running OK and just has a clogged jet, then go ahead and remove each jet (all four of them) and blast some carb cleaner through them (use the needle tube on an aerosol can). Once the jet is blasted and before you put it back, go to the carb and blast straight into the hole where the jet resides - several seconds should do it, then replace the jet just as it was.
4. * Carb cleaner in the gas tank takes at least a tankful run through the engine to make a difference, maybe two tanks, and that's at a high concentration. I prefer Seafoam, but CRC or Gummout should both work OK but remember, it takes TIME for it to work. It's always faster to remove the jets and blast them with carb cleaner (aerosol can with needle tube) and replace them. Don't forget to gently turn the mixture screws all the way in til they hit bottom while counting 1/4 turns til they stop so you'll know where they were to replace them at the same point, then remove them and blast.
5. Anything beyond these four steps would, I believe, be getting into the advanced range and you might strongly consider taking the car to someone experienced on carburetors to help out as you might also be looking at a potential vacuum leak or something hard to diagnose like that. While it might be easy for him/her to diagnose and fix, the potential for inadvertently screwing something up if you attempt repairs is high and the whole point of all this is to get you back on the road, NOT get you through "Carb Tuning 201".