FYI in case anybody else is looking for a 500mm AC Fork - I ended up ordering this one from fleEbay because it was actually less expensive than Aliexpress even w/ tax:

https://www.ebay.com/itm/183907294270

That is good to know thanks - I may end up going that route.

I'm wondering if anybody has seen any Chiner 500mm axle to crown rigid forks from a fairly reputable seller out there since that would be easier?  I was looking on AliExpress and I did manage to find one but the seller had basically no history so didn't feel good about that one.  Thanks!

I just pulled the trigger on a OG-EVKIN CF-052 which has a 69.8 HA based on an approximately 486mm A-C fork.
I wanted to slacken it out just a bit with longer A-C fork (around 500mm), or possibly install an angleset or spacer puck to accomplish this, but I'm realizing that this looks like an integrated headset so I'm not sure if this would work?  I've never worked with an integrated headset, or angleset, or puck spacer before so not sure if it is possible to use an angleset or spacer puck. 

Does anybody have any leads on a 29" 500mm-ish A-C fork that is reasonably priced or have any idea if I can use an angleset or spacer puck?  Thanks for your input!

I decided to go with the OG-EVKIN CF-052 which has a 69.8 HA and 74 STA and can accept my current non-boost wheelset.  Unfortunately it is press fit BB and while I would have strongly preferred threaded, I couldn't find a frame that matched all my criteria so that was the concession I had to make.

My idea was to either get a slightly longer A-C fork (around 500mm) to slacken it out a bit more, or possibly install an angleset or spacer puck to accomplish this, but I'm realizing that this looks like an integrated headset so I'm not sure if this would work?  I've never worked with an integrated headset before so not sure if it is possible to use an angleset or spacer puck.  Does anybody happen to know?

I'm new here and was hoping to get some help / guidance w/ a project.

As stated, my goal is to build up a MTB-ish Gravel bike or Gravel-ish HT MTB on a reasonable budget.  I'm thinking:
Reasonably lightweight
Flat bars
Wide 700c (or narrow-ish 29er) wheels,
Aggressive (for gravel) geo - maybe something a bit longer and around 68-69 degree HA resembling a Cutthroat, Fezzarri Shafer, Sonder Camino, etc.
Long (for gravel) dropper

I have some useable gravel components so my 1st choice would be to find a a gravel frame that fits the bill, but I have not found anything like this in the Chinese carbon market as they all seem to be pretty much the same standard geo, but if anybody has seen anything like this please let me know

The other idea is to pick up a HT frame where the geo is in that neighborhood (something like an Epic, Alma, etc.), a suspension corrected rigid fork, preferably non-boost so can use current wheels, or maybe even pick up some new wheels if too big of a pain to convert current non-boost rear wheel to boost.  Based on my research so far, this is probably a more likely scenario, but would love to find a vendor who sells as many of the components as possible under one roof and would maybe even install the headset / BB (if PF) to save me the trouble!

If anybody has any suggestions, leads, or ideas on the best frame / vendor for this project, I would really appreciate the input.  Thanks!