there were never CTS pots used in production BG2s, according to richard mintz. his company built every single BG2. please, can you link to the photos of original BG2s that have CTS pots?
replacement parts are another story altogether, i have no info about this, except to say that i once serviced a 72 boomerang that had a correct centralab part with a '77 date code. i assume that someone had the 72 serviced by an authorized dealer who had access to the correct part.
why do they measure 30K? i don't know. but at least 10 originals fall into this pattern.
a 3/16ths diameter shaft will require some sort of rigging so that the 1/4" hole on the round gear will work.
i offered you a very fair price to provide you with a working, durable pot specially prepared to work in a boomerang, you said my price was too high.
i have a special testing rig and have collected data on at least a hundred pots for wah. who pays me for this research? i certainly don't make it up on a 6 dollar markup on a pot. all this, assuming my labor is 2.00 per hour for the prep work and mailing, not including the emails and paypal crap.
you will run into myriad problems trying to get an average log pot to work in a boomer. first off, it is a modified rev log. even harder to find than log.
second, the average taper will have insufficient travel at the treble end to allow the footswitch to engage without either damaging the pot or jumping a tooth, or both. the alternative is to leave it at less than full treble. which a 25k pot will not give you anyway ( problem #3)
4. bushing, shaft length all have to be long enough to work, or you have to find workarounds for those issues as well. 5. durability issues. 6. many pots, including the centralab originals sometimes have a defect in the trace, which causes a terrible static at the end of rotation. there are a few tricks to remedy this, but sometimes the pot simply has to have a compromised high end to avoid the noise. r mintz said that a large number of the original pots were unusable due to this defect.
another finding: the common trick of using a 100k wah pot with a 33k limiting resistor compromises the sound and foot feel. i have serviced many BG2s that came to me with this 'fix'. the limiting resistor exacerbates the kink in the sweep- it compresses it even further. you completely lose the expressive extended mid emphasis and sweet spot that boomers are famous for. there is more to this, but that is the cliff notes version.
sounds like you are doing your own research, this will be a fun experience, i am sure.