Honda-SOHC

Did realise a squirrel bladder was so big 

Perhaps they've been dahn-t-pub.

Agree with likey cause being unintended force in wrong direction whilst tightening bolts unevenly, or missing alignment of sprocket throughout the assembley/ location part.

Good advice to get them all but fully assembled by fingers before just a tightening torque at end to finish the work.

Many years ago, watched someone tightening a jaguar XK camshaft (they are very long) by just going along from one end to the other in assembly, only to snap it in half as it bent against one of the valve springs.

Very strong in direction needed, but simply vulnerable to bending forces that are not part of running when in use.

General principle of dry sump is that the return/scavenge side of pump will always have more capacity than pressure, else all the oil would end up in the sump during running.

Pressure side MUST always have feed as that's the only route to fill oil galleries. The tank should NEVER be evacuated as its imperative to always keep that feed established and not allow air into the pump head pressure side.

After oil change on these 750, the filled tank will drop initially as it brings filter housing etc back to being full after change. Then checking to see what level you've got after that.

With cold oil though, you'll likely see variance (especially with clear feed tank to observe) as the thicker oil will take time to cascade back down to the sump after exiting the feed system through crank, camshaft chamber etc. The F2 more so in comparison to earlier 750 as they deleted half the drain back holes from the head to base of engine. If it's not reached the pickup, then the scavenge can't return it to tank for you to see there.

If you're not running it (getting oil warm) tgen it will look like you describe, especially with new oil at it's best viscosity characteristic. Leaving it to slowly collect back in sump will,then show increased return as scavenge pumpmhas it available immediately. 

This is different from in use "sumping" in which the oil is at correct level in tank at engine stop, only to leak from the tank perhaps overnight, to wrongly end up in the sump. It should have system protection to avoid this specific trait.

If you're not running it to get it warm, then that looks normal as described in first post. Letting it warm up should produce a competent and fairly equal level in the tank whether running or switched off after oil is at running temperature.

To emphasise though, the feed from tank should NEVER be voided whether hot, cold, new or old old, its the ONLY supply to bearings the engine has. There's no lubrication otherwise, all dry system are designed with tank  capacity and flow direction to keep this aspect as an absolute requirement.

What a lovely little twin there Ash.

Sounds really good running too (through headphones) my father's friends had various different Honda twins before I was old enough to ride bikes, funny how that sound memory is still so clear from then.

Interesting thread, always good to hear what other's are using.

This may be of help https://www.permabond.com/resource-center/rubber-bonding-type-rubber-unknown/ I've not used this or the previous suggestions, so curious as to outcome.

Have tried to repair or revive indicator stalks before, with notable and probably 100% failure  the rubber does appear to loose it's properties and not ultimately absorb adhesive when it gets harder though.

Unsure of the adjuster pitch, but likely 1mm from memory.

1/2 turn is only 0.5 mm linear for wheel spindle, and so about 1/4 mm from the top and bottom chain run each. Doesn't seem out of the ordinary.

A new chain will "spread" its bushes etc under first period of loading, dependent on it's manufacturing tolerances, also just how much lubricant was in each pin site.

Reality check, put a ratchet strap over frame from each side of swing arm, pull it up so that wheel spindle is in line with front sprocket and swing arm pivot, then check how much slack is there in the chain run.

Too tight like that (the longest it can get to from geometry) and you'll get more variation than common. It needs about 10 mm in that situation as it'll be looser everywhere else.

Progress at least Dave. I'd still be suspicious of that book specification  torque figure on limited threads though. Essentially the steering is directly linked through the base triple to stanchion, just how much location the maximum torque could apply, along with its effect (through friction in its faces) I'm not sure.
Have you considered making a new stem for hhe damaged one, turning the factory weld off the base, inserting and welding the new item in situ ?

You could make a longer one to accommodate the new bearings etc.

For 180degree out, you could have the cam on the advance and retard spindle "flipped" as that just swaps them to that effect.