Some 1980s 80cc MX bikes also had 30mm tubes which can be either shortened or just let them poke way up through to top clamps.
Rechrome is about $150 per tube. RAD hardchroming at Sherwood Brisbane do a good job.
TY250 twinshock front end fits TY175 perfectly.
88kg with standard TY175 forks is not too bad a combination.
TY mono triple clamps are not an easy fit due to the steering stops. Nothing that welding cant fix though. I seem to remember that you end up with not much steering lock. TY mono forks have a bit better action than TY twinshock forks.
Probably need to keep the mono forks with the mono triple clamps to preserve steering geometry. Ty mono forks in TY twinshock clamps will have very little or no trail.
I would think that AG100 fork tubes would be too short, but there are many other bikes that used 30mm tubes apart from 80cc MX bikes. Early to mid 1970s jap trailbikes like the DT125 and DT175 up to D model had 30mm tubes. Suzuki TS125, TM125 and probably lots of Kawasakis too. trouble is all of them are as old as the TY175 and just as likely to be rusty.
It's not what you look at that matters, it's what you see.
Henry David Thoreau