Ian – so what got pinched? I am guessing you Helius ST hence the AM to replace it?
I think you're right about the Fox 32. As you know I was running a 150mm 32 Float on my AM for a while in a weight saving exercise but the fork was just too noodly for my build. On drops I could feel seriously worring amounts of flex and on hard steep turns the front end wanted to tuck under.
The 36 is one choice, but why not a Pike? Super stiff, a little lighter than the 36, can be made to work really well with the Push tune and you aren't paying for a whole lot of travel you won't be using.
As for the frame, well the world is your oyster. I think you're right to steer away from a Nic HT; I rode the Argon recently and while the geometry is sorted and it's super responsive, man was it harsh. Anything more than a few hours tops and you'll feel really beaten up.
I also rode the Ragley Ti. Now that is a seriously capable frame; probably the only time I've ever felt that the frame allowed me to get into a speed/drop/turn situation that the fork wasn't dealing with so well! It is amazing but then I think a big part of that is the combination of it being titanium and extremely well fabricated. By this I mean they've built in stiffness in the BB area for stomp and go power transfer, but compliance in the rear so it almost feels as if you have a modicum of suspension. It's less about there being more grip by virtue of keeping the wheel on the ground and more about isolating you from the impacts. It really did combine the best of steel and alu but the sizing is a bit of a pain as the ST is really tall IMO and even with the saddle down on its rails, I still felt I'd like to get it lower and more out of the way for better weight transfer and COG. The small might well fit me just right, but IIRC you're quite a bit taller than me.
The Ragely Ti is easy to test though.
if you wanted something custom made but not quite as ridiculously expensive as a custom Ti, then you could also consider either Independent Fabrications or maybe get in touch with 18Bikes in the Peak, as they are now doing a full custom steel option.
IF will build you anything you want with any tube set so they can accomodate your style and the loads that your bike's going to see (said as one Clydesdale class rider to another BTW 😉 )
Have fun building. Oh and by the way, how was the Mega?