In regard to your question about the main jet, the #145 should work but it will most likely be on the lean side.  A lot depends on how many disks are in the SuperTrapp and how your airbox is set up.  I would start with a #150 and groom from there.

Based on what you have shared so far, I suggest you restore the carb to stock configuration.  Seems like there has been a lot of fiddling around in its prior history.  You need to get it back to baseline and start from there.

You should have a #52.5 pilot jet, a #145 main jet, a X-7M needle jet, a 5C39 slide needle, a #45 pilot air jet 1, a #230 pilot air jet 2, and a .024" diameter main air bleed.

It very important that you verify that the parts are genuine Suzuki parts.  Make sure your needle jet is stainless steel.  If it is brass it's not OEM and you won't have a good place to start.  It should be silver, not gold, and have emulsion holes as shown here.  Note that the thin rod is a pin gage that I was using to measure the emulsion holes.

Mikuni pilot jets come with and without air bleed holes.  You do not want air bleed holes in the side of your pilot jet.  The stock #52.5 pilot jet should work OK.  Make sure no one has installed an air bleed type pilot jet.  Your pilot jet should look like this.

In the event that your slide needle has three grooves instead of only one groove, it may be the old-style needle (5C17).  The 5C17 is good and will work fine.  It's a nice upgrade since it provides a bit more adjustment. The taper dimensions are exactly identical to the newer 5C39.  Any other slide needle is bogus.  If it doesn't have 5C39 or 5C17 stamped on the side, I suggest you not use it.

Order the parts individually.  Use only OEM needle jet and slide needle.  Genuine Mikuni jets are the safest way to go.  The aftermarket overhaul kits are sketchy at best.