I have learned a LOT here and I'm hugely grateful for all your input and advice.
1) I have now tried to feed this same film into the reel after development and in the light. It is
amazing that I got as much film as I did into that reel! There is just too much friction in these old reels for this long, slightly softer film.
(Had not realised that my tanks and reels were quite that old - they are black bakelite and the larger one is a bit gritty [blush]. Been using it forever without giving it a thought)
2) Rounding the leading film corners DOES make a big difference and I shall add that to all future workflows.
3) Keeping photoflo out of tanks is a good tip. That one will be added to my list too.
4)Have now measured and this particular 'edition' of Shanghai 220 film is 159cm long. I have to assume that is standard . . .
5) No numbers or film marks as mentioned by
@Maris above. Kinda works for me as I expose the full width of the film, but I'm happy with film markings too. (Youngster says it's cool to see that the images came from film!)
6) Have given both tanks a very thorough toothbrush scrub but they are still too gritty to take this film easily
At a first look the negatives look OK. I may need to slow my exposures even further, but that's do-able.
Bigger question is whether I want to buy a new tank and reel simply to use this film. I'm very used to my old tanks with the top twirler and side spouts. Nice and easy by the kitchen sink.
Lots to think about, as always.
Thank you all!