The PP adjustable hitch for the HA is still on their website, and still says "out of stock". Spoke with them last year and they indicated if they got a bit slow they may make a run of them. Otherwise, they are keeping up with PP demand.
Your best bet is to simply buy the drop that you need and keep the straight as a spare.
My dad got a used one and it had an 8" drop. We took it to a machine shop and had them convert it to a 2" drop. Worked like a champ. Cost around $90 IIRC. BE SURE a certified welder is doing the work.
A straight one would be more challenging to convert, as there isn't enough straight bar stock to simply cut and stack to get the drop you need.
$400 is a good price, even if you have to drop the same amount back in on it. I've bought two used, one for 400 and one for 200. Got lucky with my bar and the drop was right.
A friend of mine bought one for 800, but it lots of extras and the paint was still good.
Cliff notes: Buy the 400 as quickly as possible, it's a good deal even if you have to put money into it. FYI, HA will actually buy them back to refurbish for 500.